tlsecdsader.h File Reference

RFC 8446 section 4.2.3 ECDSA-Sig-Value DER encoding. More...

#include "qsccommon.h"
#include "tlserrors.h"

Go to the source code of this file.

Functions
QSC_EXPORT_API qsc_tls_status	qsc_tls_ecdsa_der_encode (const uint8_t *rs, size_t componentsize, uint8_t *output, size_t outlen, size_t *written)
	DER-encode a raw r||s ECDSA signature.
QSC_EXPORT_API qsc_tls_status	qsc_tls_ecdsa_der_decode (const uint8_t *der, size_t derlen, size_t componentsize, uint8_t *output, size_t outlen)
	Decode a DER-encoded ECDSA signature into raw r||s form.

Detailed Description

RFC 8446 section 4.2.3 ECDSA-Sig-Value DER encoding.

TLS 1.3 ECDSA signatures on the wire are DER-encoded as: ECDSA-Sig-Value ::= SEQUENCE { r INTEGER, s INTEGER } QSC's ecdsa primitive produces raw r||s of fixed width. These helpers convert between the two representations. INTEGER encoding rules (X.690):

• Shortest-form length.
• If the MSB of the first content byte is 1, a leading 0x00 must be prepended to distinguish positive from negative.
• Leading 0x00 bytes that are not required for disambiguation are stripped (shortest form).

Function Documentation

qsc_tls_ecdsa_der_decode()

QSC_EXPORT_API qsc_tls_status qsc_tls_ecdsa_der_decode	(	const uint8_t *	der,
		size_t	derlen,
		size_t	componentsize,
		uint8_t *	output,
		size_t	outlen )

Decode a DER-encoded ECDSA signature into raw r||s form.

Parameters

der	[const uint8_t*] DER-encoded signature.
derlen	[size_t] DER signature length.
componentsize	[size_t] Expected size of each component (defines output width).
output	[uint8_t*] Destination r||s buffer; must be at least 2*componentsize bytes.
outlen	[size_t] Capacity of output.

qsc_tls_ecdsa_der_encode()

QSC_EXPORT_API qsc_tls_status qsc_tls_ecdsa_der_encode	(	const uint8_t *	rs,
		size_t	componentsize,
		uint8_t *	output,
		size_t	outlen,
		size_t *	written )

DER-encode a raw r||s ECDSA signature.

Parameters

rs	[const uint8_t*] Raw r||s buffer, each component width bytes long.
componentsize	[size_t] Size of each component in bytes (32 for P-256, 48 for P-384, 66 for P-521).
output	[uint8_t*] Destination buffer for DER-encoded signature.
outlen	[size_t] Capacity of output.
written	[size_t*] On success, receives the DER length (variable, typically 70-72 for P-256).