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mbedtls_hmac_drbg_set_entropy_len() only matters when reseeding
The documentation of HMAC_DRBG erroneously claimed that mbedtls_hmac_drbg_set_entropy_len() had an impact on the initial seeding. This is in fact not the case: mbedtls_hmac_drbg_seed() forces the entropy length to its chosen value. Fix the documentation.
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@ -139,13 +139,13 @@ void mbedtls_hmac_drbg_init( mbedtls_hmac_drbg_context *ctx );
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* Note that SHA-256 is just as efficient as SHA-224.
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* Note that SHA-256 is just as efficient as SHA-224.
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* The security strength can be reduced if a smaller
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* The security strength can be reduced if a smaller
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* entropy length is set with
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* entropy length is set with
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* mbedtls_hmac_drbg_set_entropy_len().
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* mbedtls_hmac_drbg_set_entropy_len() afterwards.
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*
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*
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* \note The default entropy length is the security strength
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* \note The entropy length for the initial seeding is
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* (converted from bits to bytes). You can override
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* the security strength (converted from bits to bytes).
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* it mbedtls_hmac_drbg_set_entropy_len().
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* You can set a different entropy length for subsequent
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* \p f_entropy is always called with a length that is
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* seeding by calling mbedtls_hmac_drbg_set_entropy_len()
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* less than or equal to the entropy length.
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* after this function.
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*
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*
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* \note During the initial seeding, this function calls
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* \note During the initial seeding, this function calls
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* the entropy source to obtain a nonce
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* the entropy source to obtain a nonce
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@ -156,6 +156,8 @@ void mbedtls_hmac_drbg_init( mbedtls_hmac_drbg_context *ctx );
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* \param f_entropy The entropy callback, taking as arguments the
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* \param f_entropy The entropy callback, taking as arguments the
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* \p p_entropy context, the buffer to fill, and the
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* \p p_entropy context, the buffer to fill, and the
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* length of the buffer.
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* length of the buffer.
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* \p f_entropy is always called with a length that is
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* less than or equal to the entropy length.
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* \param p_entropy The entropy context to pass to \p f_entropy.
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* \param p_entropy The entropy context to pass to \p f_entropy.
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* \param custom The personalization string.
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* \param custom The personalization string.
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* This can be \c NULL, in which case the personalization
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* This can be \c NULL, in which case the personalization
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@ -222,13 +224,14 @@ void mbedtls_hmac_drbg_set_prediction_resistance( mbedtls_hmac_drbg_context *ctx
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/**
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/**
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* \brief This function sets the amount of entropy grabbed on each
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* \brief This function sets the amount of entropy grabbed on each
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* seed or reseed.
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* reseed.
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*
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*
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* During the initial seeding, mbedtls_hmac_drbg_seed() additionally grabs
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* The default value is set by mbedtls_hmac_drbg_seed().
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* half this amount to create the nonce.
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*
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*
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* The default value is given by the security strength, which depends on the
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* \note mbedtls_hmac_drbg_seed() always sets the entropy length
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* hash used. See the documentation of mbedtls_hmac_drbg_seed() for details.
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* to the default value based on the chosen MD algorithm,
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* so this function only has an effect if it is called
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* after mbedtls_hmac_drbg_seed().
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*
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*
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* \param ctx The HMAC_DRBG context.
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* \param ctx The HMAC_DRBG context.
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* \param len The amount of entropy to grab, in bytes.
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* \param len The amount of entropy to grab, in bytes.
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