PK parse/write: support keylen=0 correctly

A 0-length buffer for the key is a legitimate edge case. Ensure that
it works, even with buf=NULL. Document the key and keylen parameters.

There are already test cases for parsing an empty buffer. A subsequent
commit will add tests for writing to an empty buffer.
This commit is contained in:
Gilles Peskine 2018-12-19 17:03:28 +01:00
parent 1f19fa6f62
commit 159171b72a
3 changed files with 39 additions and 25 deletions

View file

@ -530,9 +530,13 @@ mbedtls_pk_type_t mbedtls_pk_get_type( const mbedtls_pk_context *ctx );
* \brief Parse a private key in PEM or DER format
*
* \param ctx key to be initialized
* \param key input buffer
* \param keylen size of the buffer
* (including the terminating null byte for PEM data)
* \param key Input buffer to parse.
* The buffer must contain the input exactly, with no
* extra trailing material. For PEM, the buffer must
* contain a null-terminated string.
* \param keylen Size of \b key in bytes.
* For PEM data, this includes the terminating null byte,
* so \p keylen must be equal to `strlen(key) + 1`.
* \param pwd password for decryption (optional)
* \param pwdlen size of the password
*
@ -553,9 +557,13 @@ int mbedtls_pk_parse_key( mbedtls_pk_context *ctx,
* \brief Parse a public key in PEM or DER format
*
* \param ctx key to be initialized
* \param key input buffer
* \param keylen size of the buffer
* (including the terminating null byte for PEM data)
* \param key Input buffer to parse.
* The buffer must contain the input exactly, with no
* extra trailing material. For PEM, the buffer must
* contain a null-terminated string.
* \param keylen Size of \b key in bytes.
* For PEM data, this includes the terminating null byte,
* so \p keylen must be equal to `strlen(key) + 1`.
*
* \note On entry, ctx must be empty, either freshly initialised
* with mbedtls_pk_init() or reset with mbedtls_pk_free(). If you need a
@ -643,9 +651,10 @@ int mbedtls_pk_write_pubkey_der( mbedtls_pk_context *ctx, unsigned char *buf, si
/**
* \brief Write a public key to a PEM string
*
* \param ctx public key to write away
* \param buf buffer to write to
* \param size size of the buffer
* \param ctx Context containing the public key to write.
* \param buf Buffer to write to. The output includes a
* terminating null byte.
* \param size Size of the buffer in bytes.
*
* \return 0 if successful, or a specific error code
*/
@ -654,9 +663,10 @@ int mbedtls_pk_write_pubkey_pem( mbedtls_pk_context *ctx, unsigned char *buf, si
/**
* \brief Write a private key to a PKCS#1 or SEC1 PEM string
*
* \param ctx private to write away
* \param buf buffer to write to
* \param size size of the buffer
* \param ctx Context containing the private key to write.
* \param buf Buffer to write to. The output includes a
* terminating null byte.
* \param size Size of the buffer in bytes.
*
* \return 0 if successful, or a specific error code
*/