mbedtls_rsa_pkcs1_decrypt() function
This function performs an RSA operation, then removes the message padding. It is the generic wrapper for performing a PKCS#1 decryption operation using the \p mode from the context. \deprecated It is deprecated and discouraged to call this function in #MBEDTLS_RSA_PUBLIC mode. Future versions of the library are likely to remove the \p mode argument and have it implicitly set to #MBEDTLS_RSA_PRIVATE.
Arguments
ctx
The initialized RSA context to use.
f_rng
The RNG function. If \p mode is #MBEDTLS_RSA_PRIVATE, this is used for blinding and should be provided; see mbedtls_rsa_private() for more. If \p mode is #MBEDTLS_RSA_PUBLIC, it is ignored.
p_rng
The RNG context to be passed to \p f_rng. This may be \c NULL if \p f_rng is \c NULL or doesn't need a context.
mode
The mode of operation. This must be either #MBEDTLS_RSA_PRIVATE or #MBEDTLS_RSA_PUBLIC (deprecated).
olen
The address at which to store the length of the plaintext. This must not be \c NULL.
The ciphertext buffer. This must be a readable buffer of length \c ctx->len Bytes. For example, \c 256 Bytes for an 2048-bit RSA modulus.
output
The buffer used to hold the plaintext. This must be a writable buffer of length \p output_max_len Bytes.
output_max_len
The length in Bytes of the output buffer \p output.
Return value
\c 0 on success. An \c MBEDTLS_ERR_RSA_XXX error code on failure.
Notes
The output buffer length \c output_max_len should be as large as the size \p ctx->len of \p ctx->N (for example, 128 Bytes if RSA-1024 is used) to be able to hold an arbitrary decrypted message. If it is not large enough to hold the decryption of the particular ciphertext provided, the function returns \c MBEDTLS_ERR_RSA_OUTPUT_TOO_LARGE. Alternative implementations of RSA need not support mode being set to #MBEDTLS_RSA_PUBLIC and might instead return #MBEDTLS_ERR_PLATFORM_FEATURE_UNSUPPORTED.