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Add size macros for multipart AEAD

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New macros PSA_AEAD_UPDATE_OUTPUT_SIZE, PSA_AEAD_FINISH_OUTPUT_SIZE
and PSA_AEAD_VERIFY_OUTPUT_SIZE to determine the output buffer sizes
for psa_aead_update(), psa_aead_finish() and psa_aead_verify().
This commit is contained in:
Gilles Peskine
2019-05-06 15:16:19 +02:00
parent 5211efb317
commit 49dd8d8cec
2 changed files with 87 additions and 6 deletions
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65
include/psa/crypto_sizes.h
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@@ -292,26 +292,79 @@
(plaintext_length) - PSA_AEAD_TAG_LENGTH(alg) : \
0)
/** The maximum size of the output of psa_aead_finish(), in bytes.
/** A sufficient output buffer size for psa_aead_update().
*
* If the size of the output buffer is at least this large, it is
* guaranteed that psa_aead_finish() will not fail due to an
* insufficient buffer size. The actual size of the output may be smaller
* in any given call.
*
* \param alg An AEAD algorithm
* (\c PSA_ALG_XXX value such that
* #PSA_ALG_IS_AEAD(\p alg) is true).
* \param input_length Size of the input in bytes.
*
* \return A sufficient output buffer size for the specified
* algorithm.
* If the AEAD algorithm is not recognized, return 0.
* An implementation may return either 0 or a
* correct size for an AEAD algorithm that it
* recognizes, but does not support.
*/
/* For all the AEAD modes defined in this specification, it is possible
* to emit output without delay. However, hardware may not always be
* capable of this. So for modes based on a block cipher, allow the
* implementation to delay the output until it has a full block. */
#define PSA_AEAD_UPDATE_OUTPUT_SIZE(alg, input_length) \
(PSA_ALG_IS_AEAD_ON_BLOCK_CIPHER(alg) ? \
((plaintext_length) + PSA_MAX_BLOCK_CIPHER_BLOCK_SIZE - 1) / PSA_MAX_BLOCK_CIPHER_BLOCK_SIZE : \
(plaintext_length))
/** A sufficient ciphertext buffer size for psa_aead_finish().
*
* If the size of the ciphertext buffer is at least this large, it is
* guaranteed that psa_aead_finish() will not fail due to an
* insufficient buffer size. Depending on the algorithm, the actual size of
* the ciphertext may be smaller.
* insufficient ciphertext buffer size. The actual size of the output may
* be smaller in any given call.
*
* \param alg An AEAD algorithm
* (\c PSA_ALG_XXX value such that
* #PSA_ALG_IS_AEAD(\p alg) is true).
*
* \return The maximum trailing ciphertext size for the
* \return A sufficient ciphertext buffer size for the
* specified algorithm.
* If the AEAD algorithm is not recognized, return 0.
* An implementation may return either 0 or a
* correct size for an AEAD algorithm that it
* recognizes, but does not support.
*/
#define PSA_AEAD_FINISH_OUTPUT_SIZE(alg) \
((size_t)0)
#define PSA_AEAD_FINISH_OUTPUT_SIZE(alg) \
(PSA_ALG_IS_AEAD_ON_BLOCK_CIPHER(alg) ? \
PSA_MAX_BLOCK_CIPHER_BLOCK_SIZE : \
0)
/** A sufficient plaintext buffer size for psa_aead_verify().
*
* If the size of the plaintext buffer is at least this large, it is
* guaranteed that psa_aead_verify() will not fail due to an
* insufficient plaintext buffer size. The actual size of the output may
* be smaller in any given call.
*
* \param alg An AEAD algorithm
* (\c PSA_ALG_XXX value such that
* #PSA_ALG_IS_AEAD(\p alg) is true).
*
* \return A sufficient plaintext buffer size for the
* specified algorithm.
* If the AEAD algorithm is not recognized, return 0.
* An implementation may return either 0 or a
* correct size for an AEAD algorithm that it
* recognizes, but does not support.
*/
#define PSA_AEAD_VERIFY_OUTPUT_SIZE(alg) \
(PSA_ALG_IS_AEAD_ON_BLOCK_CIPHER(alg) ? \
PSA_MAX_BLOCK_CIPHER_BLOCK_SIZE : \
0)
#define PSA_RSA_MINIMUM_PADDING_SIZE(alg) \
(PSA_ALG_IS_RSA_OAEP(alg) ? \