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Use one maximum key_len for all exported keys

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Signed-off-by: Max Fillinger <maximilian.fillinger@foxcrypto.com>
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Max Fillinger
2024-11-01 16:05:34 +01:00
parent a9a9e99a6b
commit c6fd1a24d2
3 changed files with 23 additions and 16 deletions
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14
include/mbedtls/ssl.h
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@ -5396,15 +5396,22 @@ int mbedtls_ssl_tls_prf(const mbedtls_tls_prf_types prf,
const unsigned char *random, size_t rlen,
unsigned char *dstbuf, size_t dlen);
#if defined(MBEDTLS_SSL_KEYING_MATERIAL_EXPORT)
/* Maximum value for key_len in mbedtls_ssl_export_keying material. Depending on the TLS
* version and the negotiated ciphersuite, larger keys could in principle be exported,
* but for simplicity, we define one limit that works in all cases. TLS 1.3 with SHA256
* has the strictest limit: 255 blocks of SHA256 output, or 8160 bytes. */
#define MBEDTLS_SSL_EXPORT_MAX_KEY_LEN 8160
/**
* \brief TLS-Exporter to derive shared symmetric keys between server and client.
*
* \param ssl SSL context from which to export keys. Must have finished the handshake.
* \param out Output buffer of length at least key_len bytes.
* \param key_len Length of the key to generate in bytes. In TLS 1.3, this can be at most
* 8160 if SHA256 is used as hash function or 12240 if SHA384 is used.
* \param key_len Length of the key to generate in bytes, must be at most
* MBEDTLS_SSL_EXPORT_MAX_KEY_LEN (8160).
* \param label Label for which to generate the key of length label_len.
* \param label_len Length of label in bytes. Must be < 251 in TLS 1.3.
* \param label_len Length of label in bytes. Must be at most 250 in TLS 1.3.
* \param context Context of the key. Can be NULL if context_len or use_context is 0.
* \param context_len Length of context. Must be < 2^16 in TLS 1.2.
* \param use_context Indicates if a context should be used in deriving the key.
@ -5416,7 +5423,6 @@ int mbedtls_ssl_tls_prf(const mbedtls_tls_prf_types prf,
*
* \return 0 on success. An SSL specific error on failure.
*/
#if defined(MBEDTLS_SSL_KEYING_MATERIAL_EXPORT)
int mbedtls_ssl_export_keying_material(mbedtls_ssl_context *ssl,
uint8_t *out, const size_t key_len,
const char *label, const size_t label_len,