library/gcm.c

/*
 *  NIST SP800-38D compliant GCM implementation
 *
 *  Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
 *  SPDX-License-Identifier: Apache-2.0
 *
 *  Licensed under the Apache License, Version 2.0 (the "License"); you may
 *  not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *  http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 *  This file is part of Mbed Crypto (https://tls.mbed.org)
 */

/*
 * http://csrc.nist.gov/publications/nistpubs/800-38D/SP-800-38D.pdf
 *
 * See also:
 * [MGV] http://csrc.nist.gov/groups/ST/toolkit/BCM/documents/proposedmodes/gcm/gcm-revised-spec.pdf
 *
 * We use the algorithm described as Shoup's method with 4-bit tables in
 * [MGV] 4.1, pp. 12-13, to enhance speed without using too much memory.
 */

#if !defined(MBEDCRYPTO_CONFIG_FILE)
#include "mbedcrypto/config.h"
#else
#include MBEDCRYPTO_CONFIG_FILE
#endif

#if defined(MBEDCRYPTO_GCM_C)

#include "mbedcrypto/gcm.h"
#include "mbedcrypto/platform_util.h"

#include <string.h>

#if defined(MBEDCRYPTO_AESNI_C)
#include "mbedcrypto/aesni.h"
#endif

#if defined(MBEDCRYPTO_SELF_TEST) && defined(MBEDCRYPTO_AES_C)
#include "mbedcrypto/aes.h"
#if defined(MBEDCRYPTO_PLATFORM_C)
#include "mbedcrypto/platform.h"
#else
#include <stdio.h>
#define mbedcrypto_printf printf
#endif /* MBEDCRYPTO_PLATFORM_C */
#endif /* MBEDCRYPTO_SELF_TEST && MBEDCRYPTO_AES_C */

#if !defined(MBEDCRYPTO_GCM_ALT)

/*
 * 32-bit integer manipulation macros (big endian)
 */
#ifndef GET_UINT32_BE
#define GET_UINT32_BE(n,b,i)                            \
{                                                       \
    (n) = ( (uint32_t) (b)[(i)    ] << 24 )             \
        | ( (uint32_t) (b)[(i) + 1] << 16 )             \
        | ( (uint32_t) (b)[(i) + 2] <<  8 )             \
        | ( (uint32_t) (b)[(i) + 3]       );            \
}
#endif

#ifndef PUT_UINT32_BE
#define PUT_UINT32_BE(n,b,i)                            \
{                                                       \
    (b)[(i)    ] = (unsigned char) ( (n) >> 24 );       \
    (b)[(i) + 1] = (unsigned char) ( (n) >> 16 );       \
    (b)[(i) + 2] = (unsigned char) ( (n) >>  8 );       \
    (b)[(i) + 3] = (unsigned char) ( (n)       );       \
}
#endif

/*
 * Initialize a context
 */
void mbedcrypto_gcm_init( mbedcrypto_gcm_context *ctx )
{
    memset( ctx, 0, sizeof( mbedcrypto_gcm_context ) );
}

/*
 * Precompute small multiples of H, that is set
 *      HH[i] || HL[i] = H times i,
 * where i is seen as a field element as in [MGV], ie high-order bits
 * correspond to low powers of P. The result is stored in the same way, that
 * is the high-order bit of HH corresponds to P^0 and the low-order bit of HL
 * corresponds to P^127.
 */
static int gcm_gen_table( mbedcrypto_gcm_context *ctx )
{
    int ret, i, j;
    uint64_t hi, lo;
    uint64_t vl, vh;
    unsigned char h[16];
    size_t olen = 0;

    memset( h, 0, 16 );
    if( ( ret = mbedcrypto_cipher_update( &ctx->cipher_ctx, h, 16, h, &olen ) ) != 0 )
        return( ret );

    /* pack h as two 64-bits ints, big-endian */
    GET_UINT32_BE( hi, h,  0  );
    GET_UINT32_BE( lo, h,  4  );
    vh = (uint64_t) hi << 32 | lo;

    GET_UINT32_BE( hi, h,  8  );
    GET_UINT32_BE( lo, h,  12 );
    vl = (uint64_t) hi << 32 | lo;

    /* 8 = 1000 corresponds to 1 in GF(2^128) */
    ctx->HL[8] = vl;
    ctx->HH[8] = vh;

#if defined(MBEDCRYPTO_AESNI_C) && defined(MBEDCRYPTO_HAVE_X86_64)
    /* With CLMUL support, we need only h, not the rest of the table */
    if( mbedcrypto_aesni_has_support( MBEDCRYPTO_AESNI_CLMUL ) )
        return( 0 );
#endif

    /* 0 corresponds to 0 in GF(2^128) */
    ctx->HH[0] = 0;
    ctx->HL[0] = 0;

    for( i = 4; i > 0; i >>= 1 )
    {
        uint32_t T = ( vl & 1 ) * 0xe1000000U;
        vl  = ( vh << 63 ) | ( vl >> 1 );
        vh  = ( vh >> 1 ) ^ ( (uint64_t) T << 32);

        ctx->HL[i] = vl;
        ctx->HH[i] = vh;
    }

    for( i = 2; i <= 8; i *= 2 )
    {
        uint64_t *HiL = ctx->HL + i, *HiH = ctx->HH + i;
        vh = *HiH;
        vl = *HiL;
        for( j = 1; j < i; j++ )
        {
            HiH[j] = vh ^ ctx->HH[j];
            HiL[j] = vl ^ ctx->HL[j];
        }
    }

    return( 0 );
}

int mbedcrypto_gcm_setkey( mbedcrypto_gcm_context *ctx,
                        mbedcrypto_cipher_id_t cipher,
                        const unsigned char *key,
                        unsigned int keybits )
{
    int ret;
    const mbedcrypto_cipher_info_t *cipher_info;

    cipher_info = mbedcrypto_cipher_info_from_values( cipher, keybits, MBEDCRYPTO_MODE_ECB );
    if( cipher_info == NULL )
        return( MBEDCRYPTO_ERR_GCM_BAD_INPUT );

    if( cipher_info->block_size != 16 )
        return( MBEDCRYPTO_ERR_GCM_BAD_INPUT );

    mbedcrypto_cipher_free( &ctx->cipher_ctx );

    if( ( ret = mbedcrypto_cipher_setup( &ctx->cipher_ctx, cipher_info ) ) != 0 )
        return( ret );

    if( ( ret = mbedcrypto_cipher_setkey( &ctx->cipher_ctx, key, keybits,
                               MBEDCRYPTO_ENCRYPT ) ) != 0 )
    {
        return( ret );
    }

    if( ( ret = gcm_gen_table( ctx ) ) != 0 )
        return( ret );

    return( 0 );
}

/*
 * Shoup's method for multiplication use this table with
 *      last4[x] = x times P^128
 * where x and last4[x] are seen as elements of GF(2^128) as in [MGV]
 */
static const uint64_t last4[16] =
{
    0x0000, 0x1c20, 0x3840, 0x2460,
    0x7080, 0x6ca0, 0x48c0, 0x54e0,
    0xe100, 0xfd20, 0xd940, 0xc560,
    0x9180, 0x8da0, 0xa9c0, 0xb5e0
};

/*
 * Sets output to x times H using the precomputed tables.
 * x and output are seen as elements of GF(2^128) as in [MGV].
 */
static void gcm_mult( mbedcrypto_gcm_context *ctx, const unsigned char x[16],
                      unsigned char output[16] )
{
    int i = 0;
    unsigned char lo, hi, rem;
    uint64_t zh, zl;

#if defined(MBEDCRYPTO_AESNI_C) && defined(MBEDCRYPTO_HAVE_X86_64)
    if( mbedcrypto_aesni_has_support( MBEDCRYPTO_AESNI_CLMUL ) ) {
        unsigned char h[16];

        PUT_UINT32_BE( ctx->HH[8] >> 32, h,  0 );
        PUT_UINT32_BE( ctx->HH[8],       h,  4 );
        PUT_UINT32_BE( ctx->HL[8] >> 32, h,  8 );
        PUT_UINT32_BE( ctx->HL[8],       h, 12 );

        mbedcrypto_aesni_gcm_mult( output, x, h );
        return;
    }
#endif /* MBEDCRYPTO_AESNI_C && MBEDCRYPTO_HAVE_X86_64 */

    lo = x[15] & 0xf;

    zh = ctx->HH[lo];
    zl = ctx->HL[lo];

    for( i = 15; i >= 0; i-- )
    {
        lo = x[i] & 0xf;
        hi = x[i] >> 4;

        if( i != 15 )
        {
            rem = (unsigned char) zl & 0xf;
            zl = ( zh << 60 ) | ( zl >> 4 );
            zh = ( zh >> 4 );
            zh ^= (uint64_t) last4[rem] << 48;
            zh ^= ctx->HH[lo];
            zl ^= ctx->HL[lo];

        }

        rem = (unsigned char) zl & 0xf;
        zl = ( zh << 60 ) | ( zl >> 4 );
        zh = ( zh >> 4 );
        zh ^= (uint64_t) last4[rem] << 48;
        zh ^= ctx->HH[hi];
        zl ^= ctx->HL[hi];
    }

    PUT_UINT32_BE( zh >> 32, output, 0 );
    PUT_UINT32_BE( zh, output, 4 );
    PUT_UINT32_BE( zl >> 32, output, 8 );
    PUT_UINT32_BE( zl, output, 12 );
}

int mbedcrypto_gcm_starts( mbedcrypto_gcm_context *ctx,
                int mode,
                const unsigned char *iv,
                size_t iv_len,
                const unsigned char *add,
                size_t add_len )
{
    int ret;
    unsigned char work_buf[16];
    size_t i;
    const unsigned char *p;
    size_t use_len, olen = 0;

    /* IV and AD are limited to 2^64 bits, so 2^61 bytes */
    /* IV is not allowed to be zero length */
    if( iv_len == 0 ||
      ( (uint64_t) iv_len  ) >> 61 != 0 ||
      ( (uint64_t) add_len ) >> 61 != 0 )
    {
        return( MBEDCRYPTO_ERR_GCM_BAD_INPUT );
    }

    memset( ctx->y, 0x00, sizeof(ctx->y) );
    memset( ctx->buf, 0x00, sizeof(ctx->buf) );

    ctx->mode = mode;
    ctx->len = 0;
    ctx->add_len = 0;

    if( iv_len == 12 )
    {
        memcpy( ctx->y, iv, iv_len );
        ctx->y[15] = 1;
    }
    else
    {
        memset( work_buf, 0x00, 16 );
        PUT_UINT32_BE( iv_len * 8, work_buf, 12 );

        p = iv;
        while( iv_len > 0 )
        {
            use_len = ( iv_len < 16 ) ? iv_len : 16;

            for( i = 0; i < use_len; i++ )
                ctx->y[i] ^= p[i];

            gcm_mult( ctx, ctx->y, ctx->y );

            iv_len -= use_len;
            p += use_len;
        }

        for( i = 0; i < 16; i++ )
            ctx->y[i] ^= work_buf[i];

        gcm_mult( ctx, ctx->y, ctx->y );
    }

    if( ( ret = mbedcrypto_cipher_update( &ctx->cipher_ctx, ctx->y, 16, ctx->base_ectr,
                             &olen ) ) != 0 )
    {
        return( ret );
    }

    ctx->add_len = add_len;
    p = add;
    while( add_len > 0 )
    {
        use_len = ( add_len < 16 ) ? add_len : 16;

        for( i = 0; i < use_len; i++ )
            ctx->buf[i] ^= p[i];

        gcm_mult( ctx, ctx->buf, ctx->buf );

        add_len -= use_len;
        p += use_len;
    }

    return( 0 );
}

int mbedcrypto_gcm_update( mbedcrypto_gcm_context *ctx,
                size_t length,
                const unsigned char *input,
                unsigned char *output )
{
    int ret;
    unsigned char ectr[16];
    size_t i;
    const unsigned char *p;
    unsigned char *out_p = output;
    size_t use_len, olen = 0;

    if( output > input && (size_t) ( output - input ) < length )
        return( MBEDCRYPTO_ERR_GCM_BAD_INPUT );

    /* Total length is restricted to 2^39 - 256 bits, ie 2^36 - 2^5 bytes
     * Also check for possible overflow */
    if( ctx->len + length < ctx->len ||
        (uint64_t) ctx->len + length > 0xFFFFFFFE0ull )
    {
        return( MBEDCRYPTO_ERR_GCM_BAD_INPUT );
    }

    ctx->len += length;

    p = input;
    while( length > 0 )
    {
        use_len = ( length < 16 ) ? length : 16;

        for( i = 16; i > 12; i-- )
            if( ++ctx->y[i - 1] != 0 )
                break;

        if( ( ret = mbedcrypto_cipher_update( &ctx->cipher_ctx, ctx->y, 16, ectr,
                                   &olen ) ) != 0 )
        {
            return( ret );
        }

        for( i = 0; i < use_len; i++ )
        {
            if( ctx->mode == MBEDCRYPTO_GCM_DECRYPT )
                ctx->buf[i] ^= p[i];
            out_p[i] = ectr[i] ^ p[i];
            if( ctx->mode == MBEDCRYPTO_GCM_ENCRYPT )
                ctx->buf[i] ^= out_p[i];
        }

        gcm_mult( ctx, ctx->buf, ctx->buf );

        length -= use_len;
        p += use_len;
        out_p += use_len;
    }

    return( 0 );
}

int mbedcrypto_gcm_finish( mbedcrypto_gcm_context *ctx,
                unsigned char *tag,
                size_t tag_len )
{
    unsigned char work_buf[16];
    size_t i;
    uint64_t orig_len = ctx->len * 8;
    uint64_t orig_add_len = ctx->add_len * 8;

    if( tag_len > 16 || tag_len < 4 )
        return( MBEDCRYPTO_ERR_GCM_BAD_INPUT );

    memcpy( tag, ctx->base_ectr, tag_len );

    if( orig_len || orig_add_len )
    {
        memset( work_buf, 0x00, 16 );

        PUT_UINT32_BE( ( orig_add_len >> 32 ), work_buf, 0  );
        PUT_UINT32_BE( ( orig_add_len       ), work_buf, 4  );
        PUT_UINT32_BE( ( orig_len     >> 32 ), work_buf, 8  );
        PUT_UINT32_BE( ( orig_len           ), work_buf, 12 );

        for( i = 0; i < 16; i++ )
            ctx->buf[i] ^= work_buf[i];

        gcm_mult( ctx, ctx->buf, ctx->buf );

        for( i = 0; i < tag_len; i++ )
            tag[i] ^= ctx->buf[i];
    }

    return( 0 );
}

int mbedcrypto_gcm_crypt_and_tag( mbedcrypto_gcm_context *ctx,
                       int mode,
                       size_t length,
                       const unsigned char *iv,
                       size_t iv_len,
                       const unsigned char *add,
                       size_t add_len,
                       const unsigned char *input,
                       unsigned char *output,
                       size_t tag_len,
                       unsigned char *tag )
{
    int ret;

    if( ( ret = mbedcrypto_gcm_starts( ctx, mode, iv, iv_len, add, add_len ) ) != 0 )
        return( ret );

    if( ( ret = mbedcrypto_gcm_update( ctx, length, input, output ) ) != 0 )
        return( ret );

    if( ( ret = mbedcrypto_gcm_finish( ctx, tag, tag_len ) ) != 0 )
        return( ret );

    return( 0 );
}

int mbedcrypto_gcm_auth_decrypt( mbedcrypto_gcm_context *ctx,
                      size_t length,
                      const unsigned char *iv,
                      size_t iv_len,
                      const unsigned char *add,
                      size_t add_len,
                      const unsigned char *tag,
                      size_t tag_len,
                      const unsigned char *input,
                      unsigned char *output )
{
    int ret;
    unsigned char check_tag[16];
    size_t i;
    int diff;

    if( ( ret = mbedcrypto_gcm_crypt_and_tag( ctx, MBEDCRYPTO_GCM_DECRYPT, length,
                                   iv, iv_len, add, add_len,
                                   input, output, tag_len, check_tag ) ) != 0 )
    {
        return( ret );
    }

    /* Check tag in "constant-time" */
    for( diff = 0, i = 0; i < tag_len; i++ )
        diff |= tag[i] ^ check_tag[i];

    if( diff != 0 )
    {
        mbedcrypto_platform_zeroize( output, length );
        return( MBEDCRYPTO_ERR_GCM_AUTH_FAILED );
    }

    return( 0 );
}

void mbedcrypto_gcm_free( mbedcrypto_gcm_context *ctx )
{
    mbedcrypto_cipher_free( &ctx->cipher_ctx );
    mbedcrypto_platform_zeroize( ctx, sizeof( mbedcrypto_gcm_context ) );
}

#endif /* !MBEDCRYPTO_GCM_ALT */

#if defined(MBEDCRYPTO_SELF_TEST) && defined(MBEDCRYPTO_AES_C)
/*
 * AES-GCM test vectors from:
 *
 * http://csrc.nist.gov/groups/STM/cavp/documents/mac/gcmtestvectors.zip
 */
#define MAX_TESTS   6

static const int key_index[MAX_TESTS] =
    { 0, 0, 1, 1, 1, 1 };

static const unsigned char key[MAX_TESTS][32] =
{
    { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
      0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
      0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
      0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
    { 0xfe, 0xff, 0xe9, 0x92, 0x86, 0x65, 0x73, 0x1c,
      0x6d, 0x6a, 0x8f, 0x94, 0x67, 0x30, 0x83, 0x08,
      0xfe, 0xff, 0xe9, 0x92, 0x86, 0x65, 0x73, 0x1c,
      0x6d, 0x6a, 0x8f, 0x94, 0x67, 0x30, 0x83, 0x08 },
};

static const size_t iv_len[MAX_TESTS] =
    { 12, 12, 12, 12, 8, 60 };

static const int iv_index[MAX_TESTS] =
    { 0, 0, 1, 1, 1, 2 };

static const unsigned char iv[MAX_TESTS][64] =
{
    { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
      0x00, 0x00, 0x00, 0x00 },
    { 0xca, 0xfe, 0xba, 0xbe, 0xfa, 0xce, 0xdb, 0xad,
      0xde, 0xca, 0xf8, 0x88 },
    { 0x93, 0x13, 0x22, 0x5d, 0xf8, 0x84, 0x06, 0xe5,
      0x55, 0x90, 0x9c, 0x5a, 0xff, 0x52, 0x69, 0xaa,
      0x6a, 0x7a, 0x95, 0x38, 0x53, 0x4f, 0x7d, 0xa1,
      0xe4, 0xc3, 0x03, 0xd2, 0xa3, 0x18, 0xa7, 0x28,
      0xc3, 0xc0, 0xc9, 0x51, 0x56, 0x80, 0x95, 0x39,
      0xfc, 0xf0, 0xe2, 0x42, 0x9a, 0x6b, 0x52, 0x54,
      0x16, 0xae, 0xdb, 0xf5, 0xa0, 0xde, 0x6a, 0x57,
      0xa6, 0x37, 0xb3, 0x9b },
};

static const size_t add_len[MAX_TESTS] =
    { 0, 0, 0, 20, 20, 20 };

static const int add_index[MAX_TESTS] =
    { 0, 0, 0, 1, 1, 1 };

static const unsigned char additional[MAX_TESTS][64] =
{
    { 0x00 },
    { 0xfe, 0xed, 0xfa, 0xce, 0xde, 0xad, 0xbe, 0xef,
      0xfe, 0xed, 0xfa, 0xce, 0xde, 0xad, 0xbe, 0xef,
      0xab, 0xad, 0xda, 0xd2 },
};

static const size_t pt_len[MAX_TESTS] =
    { 0, 16, 64, 60, 60, 60 };

static const int pt_index[MAX_TESTS] =
    { 0, 0, 1, 1, 1, 1 };

static const unsigned char pt[MAX_TESTS][64] =
{
    { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
      0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
    { 0xd9, 0x31, 0x32, 0x25, 0xf8, 0x84, 0x06, 0xe5,
      0xa5, 0x59, 0x09, 0xc5, 0xaf, 0xf5, 0x26, 0x9a,
      0x86, 0xa7, 0xa9, 0x53, 0x15, 0x34, 0xf7, 0xda,
      0x2e, 0x4c, 0x30, 0x3d, 0x8a, 0x31, 0x8a, 0x72,
      0x1c, 0x3c, 0x0c, 0x95, 0x95, 0x68, 0x09, 0x53,
      0x2f, 0xcf, 0x0e, 0x24, 0x49, 0xa6, 0xb5, 0x25,
      0xb1, 0x6a, 0xed, 0xf5, 0xaa, 0x0d, 0xe6, 0x57,
      0xba, 0x63, 0x7b, 0x39, 0x1a, 0xaf, 0xd2, 0x55 },
};

static const unsigned char ct[MAX_TESTS * 3][64] =
{
    { 0x00 },
    { 0x03, 0x88, 0xda, 0xce, 0x60, 0xb6, 0xa3, 0x92,
      0xf3, 0x28, 0xc2, 0xb9, 0x71, 0xb2, 0xfe, 0x78 },
    { 0x42, 0x83, 0x1e, 0xc2, 0x21, 0x77, 0x74, 0x24,
      0x4b, 0x72, 0x21, 0xb7, 0x84, 0xd0, 0xd4, 0x9c,
      0xe3, 0xaa, 0x21, 0x2f, 0x2c, 0x02, 0xa4, 0xe0,
      0x35, 0xc1, 0x7e, 0x23, 0x29, 0xac, 0xa1, 0x2e,
      0x21, 0xd5, 0x14, 0xb2, 0x54, 0x66, 0x93, 0x1c,
      0x7d, 0x8f, 0x6a, 0x5a, 0xac, 0x84, 0xaa, 0x05,
      0x1b, 0xa3, 0x0b, 0x39, 0x6a, 0x0a, 0xac, 0x97,
      0x3d, 0x58, 0xe0, 0x91, 0x47, 0x3f, 0x59, 0x85 },
    { 0x42, 0x83, 0x1e, 0xc2, 0x21, 0x77, 0x74, 0x24,
      0x4b, 0x72, 0x21, 0xb7, 0x84, 0xd0, 0xd4, 0x9c,
      0xe3, 0xaa, 0x21, 0x2f, 0x2c, 0x02, 0xa4, 0xe0,
      0x35, 0xc1, 0x7e, 0x23, 0x29, 0xac, 0xa1, 0x2e,
      0x21, 0xd5, 0x14, 0xb2, 0x54, 0x66, 0x93, 0x1c,
      0x7d, 0x8f, 0x6a, 0x5a, 0xac, 0x84, 0xaa, 0x05,
      0x1b, 0xa3, 0x0b, 0x39, 0x6a, 0x0a, 0xac, 0x97,
      0x3d, 0x58, 0xe0, 0x91 },
    { 0x61, 0x35, 0x3b, 0x4c, 0x28, 0x06, 0x93, 0x4a,
      0x77, 0x7f, 0xf5, 0x1f, 0xa2, 0x2a, 0x47, 0x55,
      0x69, 0x9b, 0x2a, 0x71, 0x4f, 0xcd, 0xc6, 0xf8,
      0x37, 0x66, 0xe5, 0xf9, 0x7b, 0x6c, 0x74, 0x23,
      0x73, 0x80, 0x69, 0x00, 0xe4, 0x9f, 0x24, 0xb2,
      0x2b, 0x09, 0x75, 0x44, 0xd4, 0x89, 0x6b, 0x42,
      0x49, 0x89, 0xb5, 0xe1, 0xeb, 0xac, 0x0f, 0x07,
      0xc2, 0x3f, 0x45, 0x98 },
    { 0x8c, 0xe2, 0x49, 0x98, 0x62, 0x56, 0x15, 0xb6,
      0x03, 0xa0, 0x33, 0xac, 0xa1, 0x3f, 0xb8, 0x94,
      0xbe, 0x91, 0x12, 0xa5, 0xc3, 0xa2, 0x11, 0xa8,
      0xba, 0x26, 0x2a, 0x3c, 0xca, 0x7e, 0x2c, 0xa7,
      0x01, 0xe4, 0xa9, 0xa4, 0xfb, 0xa4, 0x3c, 0x90,
      0xcc, 0xdc, 0xb2, 0x81, 0xd4, 0x8c, 0x7c, 0x6f,
      0xd6, 0x28, 0x75, 0xd2, 0xac, 0xa4, 0x17, 0x03,
      0x4c, 0x34, 0xae, 0xe5 },
    { 0x00 },
    { 0x98, 0xe7, 0x24, 0x7c, 0x07, 0xf0, 0xfe, 0x41,
      0x1c, 0x26, 0x7e, 0x43, 0x84, 0xb0, 0xf6, 0x00 },
    { 0x39, 0x80, 0xca, 0x0b, 0x3c, 0x00, 0xe8, 0x41,
      0xeb, 0x06, 0xfa, 0xc4, 0x87, 0x2a, 0x27, 0x57,
      0x85, 0x9e, 0x1c, 0xea, 0xa6, 0xef, 0xd9, 0x84,
      0x62, 0x85, 0x93, 0xb4, 0x0c, 0xa1, 0xe1, 0x9c,
      0x7d, 0x77, 0x3d, 0x00, 0xc1, 0x44, 0xc5, 0x25,
      0xac, 0x61, 0x9d, 0x18, 0xc8, 0x4a, 0x3f, 0x47,
      0x18, 0xe2, 0x44, 0x8b, 0x2f, 0xe3, 0x24, 0xd9,
      0xcc, 0xda, 0x27, 0x10, 0xac, 0xad, 0xe2, 0x56 },
    { 0x39, 0x80, 0xca, 0x0b, 0x3c, 0x00, 0xe8, 0x41,
      0xeb, 0x06, 0xfa, 0xc4, 0x87, 0x2a, 0x27, 0x57,
      0x85, 0x9e, 0x1c, 0xea, 0xa6, 0xef, 0xd9, 0x84,
      0x62, 0x85, 0x93, 0xb4, 0x0c, 0xa1, 0xe1, 0x9c,
      0x7d, 0x77, 0x3d, 0x00, 0xc1, 0x44, 0xc5, 0x25,
      0xac, 0x61, 0x9d, 0x18, 0xc8, 0x4a, 0x3f, 0x47,
      0x18, 0xe2, 0x44, 0x8b, 0x2f, 0xe3, 0x24, 0xd9,
      0xcc, 0xda, 0x27, 0x10 },
    { 0x0f, 0x10, 0xf5, 0x99, 0xae, 0x14, 0xa1, 0x54,
      0xed, 0x24, 0xb3, 0x6e, 0x25, 0x32, 0x4d, 0xb8,
      0xc5, 0x66, 0x63, 0x2e, 0xf2, 0xbb, 0xb3, 0x4f,
      0x83, 0x47, 0x28, 0x0f, 0xc4, 0x50, 0x70, 0x57,
      0xfd, 0xdc, 0x29, 0xdf, 0x9a, 0x47, 0x1f, 0x75,
      0xc6, 0x65, 0x41, 0xd4, 0xd4, 0xda, 0xd1, 0xc9,
      0xe9, 0x3a, 0x19, 0xa5, 0x8e, 0x8b, 0x47, 0x3f,
      0xa0, 0xf0, 0x62, 0xf7 },
    { 0xd2, 0x7e, 0x88, 0x68, 0x1c, 0xe3, 0x24, 0x3c,
      0x48, 0x30, 0x16, 0x5a, 0x8f, 0xdc, 0xf9, 0xff,
      0x1d, 0xe9, 0xa1, 0xd8, 0xe6, 0xb4, 0x47, 0xef,
      0x6e, 0xf7, 0xb7, 0x98, 0x28, 0x66, 0x6e, 0x45,
      0x81, 0xe7, 0x90, 0x12, 0xaf, 0x34, 0xdd, 0xd9,
      0xe2, 0xf0, 0x37, 0x58, 0x9b, 0x29, 0x2d, 0xb3,
      0xe6, 0x7c, 0x03, 0x67, 0x45, 0xfa, 0x22, 0xe7,
      0xe9, 0xb7, 0x37, 0x3b },
    { 0x00 },
    { 0xce, 0xa7, 0x40, 0x3d, 0x4d, 0x60, 0x6b, 0x6e,
      0x07, 0x4e, 0xc5, 0xd3, 0xba, 0xf3, 0x9d, 0x18 },
    { 0x52, 0x2d, 0xc1, 0xf0, 0x99, 0x56, 0x7d, 0x07,
      0xf4, 0x7f, 0x37, 0xa3, 0x2a, 0x84, 0x42, 0x7d,
      0x64, 0x3a, 0x8c, 0xdc, 0xbf, 0xe5, 0xc0, 0xc9,
      0x75, 0x98, 0xa2, 0xbd, 0x25, 0x55, 0xd1, 0xaa,
      0x8c, 0xb0, 0x8e, 0x48, 0x59, 0x0d, 0xbb, 0x3d,
      0xa7, 0xb0, 0x8b, 0x10, 0x56, 0x82, 0x88, 0x38,
      0xc5, 0xf6, 0x1e, 0x63, 0x93, 0xba, 0x7a, 0x0a,
      0xbc, 0xc9, 0xf6, 0x62, 0x89, 0x80, 0x15, 0xad },
    { 0x52, 0x2d, 0xc1, 0xf0, 0x99, 0x56, 0x7d, 0x07,
      0xf4, 0x7f, 0x37, 0xa3, 0x2a, 0x84, 0x42, 0x7d,
      0x64, 0x3a, 0x8c, 0xdc, 0xbf, 0xe5, 0xc0, 0xc9,
      0x75, 0x98, 0xa2, 0xbd, 0x25, 0x55, 0xd1, 0xaa,
      0x8c, 0xb0, 0x8e, 0x48, 0x59, 0x0d, 0xbb, 0x3d,
      0xa7, 0xb0, 0x8b, 0x10, 0x56, 0x82, 0x88, 0x38,
      0xc5, 0xf6, 0x1e, 0x63, 0x93, 0xba, 0x7a, 0x0a,
      0xbc, 0xc9, 0xf6, 0x62 },
    { 0xc3, 0x76, 0x2d, 0xf1, 0xca, 0x78, 0x7d, 0x32,
      0xae, 0x47, 0xc1, 0x3b, 0xf1, 0x98, 0x44, 0xcb,
      0xaf, 0x1a, 0xe1, 0x4d, 0x0b, 0x97, 0x6a, 0xfa,
      0xc5, 0x2f, 0xf7, 0xd7, 0x9b, 0xba, 0x9d, 0xe0,
      0xfe, 0xb5, 0x82, 0xd3, 0x39, 0x34, 0xa4, 0xf0,
      0x95, 0x4c, 0xc2, 0x36, 0x3b, 0xc7, 0x3f, 0x78,
      0x62, 0xac, 0x43, 0x0e, 0x64, 0xab, 0xe4, 0x99,
      0xf4, 0x7c, 0x9b, 0x1f },
    { 0x5a, 0x8d, 0xef, 0x2f, 0x0c, 0x9e, 0x53, 0xf1,
      0xf7, 0x5d, 0x78, 0x53, 0x65, 0x9e, 0x2a, 0x20,
      0xee, 0xb2, 0xb2, 0x2a, 0xaf, 0xde, 0x64, 0x19,
      0xa0, 0x58, 0xab, 0x4f, 0x6f, 0x74, 0x6b, 0xf4,
      0x0f, 0xc0, 0xc3, 0xb7, 0x80, 0xf2, 0x44, 0x45,
      0x2d, 0xa3, 0xeb, 0xf1, 0xc5, 0xd8, 0x2c, 0xde,
      0xa2, 0x41, 0x89, 0x97, 0x20, 0x0e, 0xf8, 0x2e,
      0x44, 0xae, 0x7e, 0x3f },
};

static const unsigned char tag[MAX_TESTS * 3][16] =
{
    { 0x58, 0xe2, 0xfc, 0xce, 0xfa, 0x7e, 0x30, 0x61,
      0x36, 0x7f, 0x1d, 0x57, 0xa4, 0xe7, 0x45, 0x5a },
    { 0xab, 0x6e, 0x47, 0xd4, 0x2c, 0xec, 0x13, 0xbd,
      0xf5, 0x3a, 0x67, 0xb2, 0x12, 0x57, 0xbd, 0xdf },
    { 0x4d, 0x5c, 0x2a, 0xf3, 0x27, 0xcd, 0x64, 0xa6,
      0x2c, 0xf3, 0x5a, 0xbd, 0x2b, 0xa6, 0xfa, 0xb4 },
    { 0x5b, 0xc9, 0x4f, 0xbc, 0x32, 0x21, 0xa5, 0xdb,
      0x94, 0xfa, 0xe9, 0x5a, 0xe7, 0x12, 0x1a, 0x47 },
    { 0x36, 0x12, 0xd2, 0xe7, 0x9e, 0x3b, 0x07, 0x85,
      0x56, 0x1b, 0xe1, 0x4a, 0xac, 0xa2, 0xfc, 0xcb },
    { 0x61, 0x9c, 0xc5, 0xae, 0xff, 0xfe, 0x0b, 0xfa,
      0x46, 0x2a, 0xf4, 0x3c, 0x16, 0x99, 0xd0, 0x50 },
    { 0xcd, 0x33, 0xb2, 0x8a, 0xc7, 0x73, 0xf7, 0x4b,
      0xa0, 0x0e, 0xd1, 0xf3, 0x12, 0x57, 0x24, 0x35 },
    { 0x2f, 0xf5, 0x8d, 0x80, 0x03, 0x39, 0x27, 0xab,
      0x8e, 0xf4, 0xd4, 0x58, 0x75, 0x14, 0xf0, 0xfb },
    { 0x99, 0x24, 0xa7, 0xc8, 0x58, 0x73, 0x36, 0xbf,
      0xb1, 0x18, 0x02, 0x4d, 0xb8, 0x67, 0x4a, 0x14 },
    { 0x25, 0x19, 0x49, 0x8e, 0x80, 0xf1, 0x47, 0x8f,
      0x37, 0xba, 0x55, 0xbd, 0x6d, 0x27, 0x61, 0x8c },
    { 0x65, 0xdc, 0xc5, 0x7f, 0xcf, 0x62, 0x3a, 0x24,
      0x09, 0x4f, 0xcc, 0xa4, 0x0d, 0x35, 0x33, 0xf8 },
    { 0xdc, 0xf5, 0x66, 0xff, 0x29, 0x1c, 0x25, 0xbb,
      0xb8, 0x56, 0x8f, 0xc3, 0xd3, 0x76, 0xa6, 0xd9 },
    { 0x53, 0x0f, 0x8a, 0xfb, 0xc7, 0x45, 0x36, 0xb9,
      0xa9, 0x63, 0xb4, 0xf1, 0xc4, 0xcb, 0x73, 0x8b },
    { 0xd0, 0xd1, 0xc8, 0xa7, 0x99, 0x99, 0x6b, 0xf0,
      0x26, 0x5b, 0x98, 0xb5, 0xd4, 0x8a, 0xb9, 0x19 },
    { 0xb0, 0x94, 0xda, 0xc5, 0xd9, 0x34, 0x71, 0xbd,
      0xec, 0x1a, 0x50, 0x22, 0x70, 0xe3, 0xcc, 0x6c },
    { 0x76, 0xfc, 0x6e, 0xce, 0x0f, 0x4e, 0x17, 0x68,
      0xcd, 0xdf, 0x88, 0x53, 0xbb, 0x2d, 0x55, 0x1b },
    { 0x3a, 0x33, 0x7d, 0xbf, 0x46, 0xa7, 0x92, 0xc4,
      0x5e, 0x45, 0x49, 0x13, 0xfe, 0x2e, 0xa8, 0xf2 },
    { 0xa4, 0x4a, 0x82, 0x66, 0xee, 0x1c, 0x8e, 0xb0,
      0xc8, 0xb5, 0xd4, 0xcf, 0x5a, 0xe9, 0xf1, 0x9a },
};

int mbedcrypto_gcm_self_test( int verbose )
{
    mbedcrypto_gcm_context ctx;
    unsigned char buf[64];
    unsigned char tag_buf[16];
    int i, j, ret;
    mbedcrypto_cipher_id_t cipher = MBEDCRYPTO_CIPHER_ID_AES;

    for( j = 0; j < 3; j++ )
    {
        int key_len = 128 + 64 * j;

        for( i = 0; i < MAX_TESTS; i++ )
        {
            mbedcrypto_gcm_init( &ctx );

            if( verbose != 0 )
                mbedcrypto_printf( "  AES-GCM-%3d #%d (%s): ",
                                key_len, i, "enc" );

            ret = mbedcrypto_gcm_setkey( &ctx, cipher, key[key_index[i]],
                                      key_len );
            /*
             * AES-192 is an optional feature that may be unavailable when
             * there is an alternative underlying implementation i.e. when
             * MBEDCRYPTO_AES_ALT is defined.
             */
            if( ret == MBEDCRYPTO_ERR_AES_FEATURE_UNAVAILABLE && key_len == 192 )
            {
                mbedcrypto_printf( "skipped\n" );
                break;
            }
            else if( ret != 0 )
            {
                goto exit;
            }

            ret = mbedcrypto_gcm_crypt_and_tag( &ctx, MBEDCRYPTO_GCM_ENCRYPT,
                                        pt_len[i],
                                        iv[iv_index[i]], iv_len[i],
                                        additional[add_index[i]], add_len[i],
                                        pt[pt_index[i]], buf, 16, tag_buf );
            if( ret != 0 )
                goto exit;

            if ( memcmp( buf, ct[j * 6 + i], pt_len[i] ) != 0 ||
                 memcmp( tag_buf, tag[j * 6 + i], 16 ) != 0 )
            {
                ret = 1;
                goto exit;
            }

            mbedcrypto_gcm_free( &ctx );

            if( verbose != 0 )
                mbedcrypto_printf( "passed\n" );

            mbedcrypto_gcm_init( &ctx );

            if( verbose != 0 )
                mbedcrypto_printf( "  AES-GCM-%3d #%d (%s): ",
                                key_len, i, "dec" );

            ret = mbedcrypto_gcm_setkey( &ctx, cipher, key[key_index[i]],
                                      key_len );
            if( ret != 0 )
                goto exit;

            ret = mbedcrypto_gcm_crypt_and_tag( &ctx, MBEDCRYPTO_GCM_DECRYPT,
                                        pt_len[i],
                                        iv[iv_index[i]], iv_len[i],
                                        additional[add_index[i]], add_len[i],
                                        ct[j * 6 + i], buf, 16, tag_buf );

            if( ret != 0 )
                goto exit;

            if( memcmp( buf, pt[pt_index[i]], pt_len[i] ) != 0 ||
                memcmp( tag_buf, tag[j * 6 + i], 16 ) != 0 )
            {
                ret = 1;
                goto exit;
            }

            mbedcrypto_gcm_free( &ctx );

            if( verbose != 0 )
                mbedcrypto_printf( "passed\n" );

            mbedcrypto_gcm_init( &ctx );

            if( verbose != 0 )
                mbedcrypto_printf( "  AES-GCM-%3d #%d split (%s): ",
                                key_len, i, "enc" );

            ret = mbedcrypto_gcm_setkey( &ctx, cipher, key[key_index[i]],
                                      key_len );
            if( ret != 0 )
                goto exit;

            ret = mbedcrypto_gcm_starts( &ctx, MBEDCRYPTO_GCM_ENCRYPT,
                                      iv[iv_index[i]], iv_len[i],
                                      additional[add_index[i]], add_len[i] );
            if( ret != 0 )
                goto exit;

            if( pt_len[i] > 32 )
            {
                size_t rest_len = pt_len[i] - 32;
                ret = mbedcrypto_gcm_update( &ctx, 32, pt[pt_index[i]], buf );
                if( ret != 0 )
                    goto exit;

                ret = mbedcrypto_gcm_update( &ctx, rest_len, pt[pt_index[i]] + 32,
                                  buf + 32 );
                if( ret != 0 )
                    goto exit;
            }
            else
            {
                ret = mbedcrypto_gcm_update( &ctx, pt_len[i], pt[pt_index[i]], buf );
                if( ret != 0 )
                    goto exit;
            }

            ret = mbedcrypto_gcm_finish( &ctx, tag_buf, 16 );
            if( ret != 0 )
                goto exit;

            if( memcmp( buf, ct[j * 6 + i], pt_len[i] ) != 0 ||
                memcmp( tag_buf, tag[j * 6 + i], 16 ) != 0 )
            {
                ret = 1;
                goto exit;
            }

            mbedcrypto_gcm_free( &ctx );

            if( verbose != 0 )
                mbedcrypto_printf( "passed\n" );

            mbedcrypto_gcm_init( &ctx );

            if( verbose != 0 )
                mbedcrypto_printf( "  AES-GCM-%3d #%d split (%s): ",
                                key_len, i, "dec" );

            ret = mbedcrypto_gcm_setkey( &ctx, cipher, key[key_index[i]],
                                      key_len );
            if( ret != 0 )
                goto exit;

            ret = mbedcrypto_gcm_starts( &ctx, MBEDCRYPTO_GCM_DECRYPT,
                              iv[iv_index[i]], iv_len[i],
                              additional[add_index[i]], add_len[i] );
            if( ret != 0 )
                goto exit;

            if( pt_len[i] > 32 )
            {
                size_t rest_len = pt_len[i] - 32;
                ret = mbedcrypto_gcm_update( &ctx, 32, ct[j * 6 + i], buf );
                if( ret != 0 )
                    goto exit;

                ret = mbedcrypto_gcm_update( &ctx, rest_len, ct[j * 6 + i] + 32,
                                          buf + 32 );
                if( ret != 0 )
                    goto exit;
            }
            else
            {
                ret = mbedcrypto_gcm_update( &ctx, pt_len[i], ct[j * 6 + i],
                                          buf );
                if( ret != 0 )
                    goto exit;
            }

            ret = mbedcrypto_gcm_finish( &ctx, tag_buf, 16 );
            if( ret != 0 )
                goto exit;

            if( memcmp( buf, pt[pt_index[i]], pt_len[i] ) != 0 ||
                memcmp( tag_buf, tag[j * 6 + i], 16 ) != 0 )
            {
                ret = 1;
                goto exit;
            }

            mbedcrypto_gcm_free( &ctx );

            if( verbose != 0 )
                mbedcrypto_printf( "passed\n" );
        }
    }

    if( verbose != 0 )
        mbedcrypto_printf( "\n" );

    ret = 0;

exit:
    if( ret != 0 )
    {
        if( verbose != 0 )
            mbedcrypto_printf( "failed\n" );
        mbedcrypto_gcm_free( &ctx );
    }

    return( ret );
}

#endif /* MBEDCRYPTO_SELF_TEST && MBEDCRYPTO_AES_C */

#endif /* MBEDCRYPTO_GCM_C */