AEAD modes such as GCM authenticate optional associated data (AAD) and produce an authentication tag, which the block-cipher encrypt/decrypt interface cannot express. Add qcrypto_cipher_setaad() and qcrypto_cipher_gettag() plus the matching backend driver hooks. The generic front-end reports an error when the selected mode's driver does not implement them, so calling them on a non-AEAD mode fails cleanly.
Signed-off-by: Jamin Lin <[email protected]> Reviewed-by: Daniel P. Berrangé <[email protected]> --- crypto/cipherpriv.h | 8 ++++++++ include/crypto/cipher.h | 36 ++++++++++++++++++++++++++++++++++++ crypto/cipher.c | 31 +++++++++++++++++++++++++++++++ 3 files changed, 75 insertions(+) diff --git a/crypto/cipherpriv.h b/crypto/cipherpriv.h index 64737ce961..c4f995f369 100644 --- a/crypto/cipherpriv.h +++ b/crypto/cipherpriv.h @@ -34,6 +34,14 @@ struct QCryptoCipherDriver { const uint8_t *iv, size_t niv, Error **errp); + int (*cipher_setaad)(QCryptoCipher *cipher, + const uint8_t *aad, size_t len, + Error **errp); + + int (*cipher_gettag)(QCryptoCipher *cipher, + uint8_t *tag, size_t len, + Error **errp); + void (*cipher_free)(QCryptoCipher *cipher); }; diff --git a/include/crypto/cipher.h b/include/crypto/cipher.h index 92939310ef..2e361411b9 100644 --- a/include/crypto/cipher.h +++ b/include/crypto/cipher.h @@ -235,4 +235,40 @@ int qcrypto_cipher_setiv(QCryptoCipher *cipher, const uint8_t *iv, size_t niv, Error **errp); +/** + * qcrypto_cipher_setaad: + * @cipher: the cipher object + * @aad: the associated data to authenticate + * @len: the length of @aad + * @errp: pointer to a NULL-initialized error object + * + * For AEAD modes such as GCM, feed the associated data (AAD) that is + * authenticated but not encrypted. It must be called after + * qcrypto_cipher_setiv() and before the first encrypt/decrypt call. It is + * an error to call this on a mode that is not an AEAD mode. + * + * Returns: 0 on success, -1 on error + */ +int qcrypto_cipher_setaad(QCryptoCipher *cipher, + const uint8_t *aad, size_t len, + Error **errp); + +/** + * qcrypto_cipher_gettag: + * @cipher: the cipher object + * @tag: buffer to receive the authentication tag + * @len: the length of @tag + * @errp: pointer to a NULL-initialized error object + * + * For AEAD modes such as GCM, read back the authentication tag computed + * over the associated data and the message. It must be called after the + * encrypt/decrypt operation. It is an error to call this on a mode that is + * not an AEAD mode. + * + * Returns: 0 on success, -1 on error + */ +int qcrypto_cipher_gettag(QCryptoCipher *cipher, + uint8_t *tag, size_t len, + Error **errp); + #endif /* QCRYPTO_CIPHER_H */ diff --git a/crypto/cipher.c b/crypto/cipher.c index 52d071a90c..67014aad6f 100644 --- a/crypto/cipher.c +++ b/crypto/cipher.c @@ -205,6 +205,37 @@ int qcrypto_cipher_setiv(QCryptoCipher *cipher, } +int qcrypto_cipher_setaad(QCryptoCipher *cipher, + const uint8_t *aad, size_t len, + Error **errp) +{ + const QCryptoCipherDriver *drv = cipher->driver; + + if (!drv->cipher_setaad) { + error_setg(errp, "The cipher mode does not support associated data"); + return -1; + } + + return drv->cipher_setaad(cipher, aad, len, errp); +} + + +int qcrypto_cipher_gettag(QCryptoCipher *cipher, + uint8_t *tag, size_t len, + Error **errp) +{ + const QCryptoCipherDriver *drv = cipher->driver; + + if (!drv->cipher_gettag) { + error_setg(errp, + "The cipher mode does not produce an authentication tag"); + return -1; + } + + return drv->cipher_gettag(cipher, tag, len, errp); +} + + void qcrypto_cipher_free(QCryptoCipher *cipher) { if (cipher) { -- 2.43.0
