Fix a/an typos in doxygen and other comments

Signed-off-by: Tom Cosgrove <tom.cosgrove@arm.com>
diff --git a/include/mbedtls/asn1write.h b/include/mbedtls/asn1write.h
index 44afae0..5da7654 100644
--- a/include/mbedtls/asn1write.h
+++ b/include/mbedtls/asn1write.h
@@ -90,7 +90,7 @@
 
 #if defined(MBEDTLS_BIGNUM_C)
 /**
- * \brief           Write a arbitrary-precision number (#MBEDTLS_ASN1_INTEGER)
+ * \brief           Write an arbitrary-precision number (#MBEDTLS_ASN1_INTEGER)
  *                  in ASN.1 format.
  *
  * \note            This function works backwards in data buffer.
diff --git a/include/mbedtls/config.h b/include/mbedtls/config.h
index 1cd6eb6..1da9802 100644
--- a/include/mbedtls/config.h
+++ b/include/mbedtls/config.h
@@ -1329,7 +1329,7 @@
  * Include backtrace information with each allocated block.
  *
  * Requires: MBEDTLS_MEMORY_BUFFER_ALLOC_C
- *           GLIBC-compatible backtrace() an backtrace_symbols() support
+ *           GLIBC-compatible backtrace() and backtrace_symbols() support
  *
  * Uncomment this macro to include backtrace information
  */
diff --git a/include/mbedtls/md.h b/include/mbedtls/md.h
index 84fafd2..9cea40a 100644
--- a/include/mbedtls/md.h
+++ b/include/mbedtls/md.h
@@ -215,7 +215,7 @@
 int mbedtls_md_setup( mbedtls_md_context_t *ctx, const mbedtls_md_info_t *md_info, int hmac );
 
 /**
- * \brief           This function clones the state of an message-digest
+ * \brief           This function clones the state of a message-digest
  *                  context.
  *
  * \note            You must call mbedtls_md_setup() on \c dst before calling
diff --git a/include/mbedtls/ripemd160.h b/include/mbedtls/ripemd160.h
index 63270d1..f890aef 100644
--- a/include/mbedtls/ripemd160.h
+++ b/include/mbedtls/ripemd160.h
@@ -74,7 +74,7 @@
 void mbedtls_ripemd160_free( mbedtls_ripemd160_context *ctx );
 
 /**
- * \brief          Clone (the state of) an RIPEMD-160 context
+ * \brief          Clone (the state of) a RIPEMD-160 context
  *
  * \param dst      The destination context
  * \param src      The context to be cloned
diff --git a/include/mbedtls/rsa.h b/include/mbedtls/rsa.h
index 062df73..8559f67 100644
--- a/include/mbedtls/rsa.h
+++ b/include/mbedtls/rsa.h
@@ -491,7 +491,7 @@
  *             the current function does not have access to them,
  *             and therefore cannot check them. See mbedtls_rsa_complete().
  *             If you want to check the consistency of the entire
- *             content of an PKCS1-encoded RSA private key, for example, you
+ *             content of a PKCS1-encoded RSA private key, for example, you
  *             should use mbedtls_rsa_validate_params() before setting
  *             up the RSA context.
  *             Additionally, if the implementation performs empirical checks,
diff --git a/include/mbedtls/ssl.h b/include/mbedtls/ssl.h
index 5064ec5..9cfb00c 100644
--- a/include/mbedtls/ssl.h
+++ b/include/mbedtls/ssl.h
@@ -652,7 +652,7 @@
  *                 for the associated \c mbedtls_ssl_get_timer_t callback to
  *                 return correct information.
  *
- * \note           If using a event-driven style of programming, an event must
+ * \note           If using an event-driven style of programming, an event must
  *                 be generated when the final delay is passed. The event must
  *                 cause a call to \c mbedtls_ssl_handshake() with the proper
  *                 SSL context to be scheduled. Care must be taken to ensure
diff --git a/include/psa/crypto.h b/include/psa/crypto.h
index d6d3e4f..faa3b9e 100644
--- a/include/psa/crypto.h
+++ b/include/psa/crypto.h
@@ -551,7 +551,7 @@
  * \retval #PSA_ERROR_INVALID_HANDLE
  *         \p key is not a valid identifier nor \c 0.
  * \retval #PSA_ERROR_COMMUNICATION_FAILURE
- *         There was an failure in communication with the cryptoprocessor.
+ *         There was a failure in communication with the cryptoprocessor.
  *         The key material may still be present in the cryptoprocessor.
  * \retval #PSA_ERROR_DATA_INVALID
  *         This error is typically a result of either storage corruption on a
diff --git a/include/psa/crypto_compat.h b/include/psa/crypto_compat.h
index 09ac488..0d18404 100644
--- a/include/psa/crypto_compat.h
+++ b/include/psa/crypto_compat.h
@@ -44,7 +44,7 @@
 
 #define PSA_KEY_HANDLE_INIT MBEDTLS_SVC_KEY_ID_INIT
 
-/** Check whether an handle is null.
+/** Check whether a handle is null.
  *
  * \param handle  Handle
  *
diff --git a/include/psa/crypto_extra.h b/include/psa/crypto_extra.h
index a48a4bb..a34d551 100644
--- a/include/psa/crypto_extra.h
+++ b/include/psa/crypto_extra.h
@@ -356,7 +356,7 @@
  */
 #define PSA_KEY_TYPE_DSA_KEY_PAIR                    ((psa_key_type_t)0x7002)
 
-/** Whether a key type is an DSA key (pair or public-only). */
+/** Whether a key type is a DSA key (pair or public-only). */
 #define PSA_KEY_TYPE_IS_DSA(type)                                       \
     (PSA_KEY_TYPE_PUBLIC_KEY_OF_KEY_PAIR(type) == PSA_KEY_TYPE_DSA_PUBLIC_KEY)
 
diff --git a/include/psa/crypto_platform.h b/include/psa/crypto_platform.h
index 66f4687..d3f518e 100644
--- a/include/psa/crypto_platform.h
+++ b/include/psa/crypto_platform.h
@@ -60,8 +60,8 @@
  *
  * The function psa_its_identifier_of_slot() in psa_crypto_storage.c that
  * translates a key identifier to a key storage file name assumes that
- * mbedtls_key_owner_id_t is an 32 bits integer. This function thus needs
- * reworking if mbedtls_key_owner_id_t is not defined as a 32 bits integer
+ * mbedtls_key_owner_id_t is a 32-bit integer. This function thus needs
+ * reworking if mbedtls_key_owner_id_t is not defined as a 32-bit integer
  * here anymore.
  */
 typedef int32_t mbedtls_key_owner_id_t;
diff --git a/include/psa/crypto_se_driver.h b/include/psa/crypto_se_driver.h
index 1dc8f9b..e34c500 100644
--- a/include/psa/crypto_se_driver.h
+++ b/include/psa/crypto_se_driver.h
@@ -394,7 +394,7 @@
                                                   psa_encrypt_or_decrypt_t direction);
 
 /** \brief A function that sets the initialization vector (if
- * necessary) for an secure element cipher operation
+ * necessary) for a secure element cipher operation
  *
  * Rationale: The `psa_se_cipher_*` operation in the PSA Cryptographic API has
  * two IV functions: one to set the IV, and one to generate it internally. The
diff --git a/include/psa/crypto_types.h b/include/psa/crypto_types.h
index 8f23021..d8a90a8 100644
--- a/include/psa/crypto_types.h
+++ b/include/psa/crypto_types.h
@@ -104,7 +104,7 @@
  * Values of this type are generally constructed by macros called
  * `PSA_DH_FAMILY_xxx`.
  *
- * The group identifier is required to create an Diffie-Hellman key using the
+ * The group identifier is required to create a Diffie-Hellman key using the
  * PSA_KEY_TYPE_DH_KEY_PAIR() or PSA_KEY_TYPE_DH_PUBLIC_KEY()
  * macros.
  *
diff --git a/include/psa/crypto_values.h b/include/psa/crypto_values.h
index 8b3a815..8e61f2f 100644
--- a/include/psa/crypto_values.h
+++ b/include/psa/crypto_values.h
@@ -1195,7 +1195,7 @@
  */
 #define PSA_ALG_CHACHA20_POLY1305               ((psa_algorithm_t)0x05100500)
 
-/* In the encoding of a AEAD algorithm, the bits corresponding to
+/* In the encoding of an AEAD algorithm, the bits corresponding to
  * PSA_ALG_AEAD_TAG_LENGTH_MASK encode the length of the AEAD tag.
  * The constants for default lengths follow this encoding.
  */