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Code Issues Releases Wiki Activity

feat(crypto): Use entire DER encoding in DER_ITEM.

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This commit is contained in:
Andrew Kozlik 2023-11-30 20:41:21 +01:00 committed by matejcik
parent 8e8f1afa85
commit 41c305f6cd
4 changed files with 29 additions and 6 deletions
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10
crypto/buffer.c
View File

@ -64,6 +64,16 @@ bool buffer_get(BUFFER_READER *buf, uint8_t *byte) {
return true;
}
bool buffer_seek(BUFFER_READER *buf, size_t pos) {
if ((buf->data == NULL) || (pos > buf->size)) {
return false;
}
buf->pos = pos;
return true;
}
bool buffer_read_buffer(BUFFER_READER *src, BUFFER_READER *dest, size_t size) {
if ((src->data == NULL) || (src->pos + size > src->size)) {
return false;

1
crypto/buffer.h
View File

@ -48,6 +48,7 @@ void buffer_writer_init(BUFFER_WRITER *buf, uint8_t *data, size_t size);
size_t __wur buffer_remaining(BUFFER_READER *buf);
bool __wur buffer_peek(const BUFFER_READER *buf, uint8_t *byte);
bool __wur buffer_get(BUFFER_READER *buf, uint8_t *byte);
bool __wur buffer_seek(BUFFER_READER *buf, size_t pos);
bool __wur buffer_read_buffer(BUFFER_READER *src, BUFFER_READER *dest,
size_t size);
void buffer_lstrip(BUFFER_READER *buf, uint8_t byte);

17
crypto/der.c
View File

@ -87,6 +87,7 @@ bool der_write_length(BUFFER_WRITER *buf, size_t len) {
}
bool der_read_item(BUFFER_READER *buf, DER_ITEM *item) {
size_t begin_pos = buf->pos;
if (!buffer_get(buf, &item->id) || ((item->id & 0x1f) == 0x1f)) {
// Multi-byte identifiers not supported.
return false;
@ -97,7 +98,13 @@ bool der_read_item(BUFFER_READER *buf, DER_ITEM *item) {
return false;
}
return buffer_read_buffer(buf, &item->cont, len);
size_t header_size = buf->pos - begin_pos;
if (!buffer_seek(buf, begin_pos) ||
!buffer_read_buffer(buf, &item->buf, header_size + len)) {
return false;
}
return buffer_seek(&item->buf, header_size);
}
// Reencode a positive integer which violates the encoding rules in Rec. ITU-T
@ -111,13 +118,13 @@ bool der_reencode_int(BUFFER_READER *reader, BUFFER_WRITER *writer) {
}
// Strip any leading 0x00 bytes.
buffer_lstrip(&item.cont, 0x00);
size_t len = buffer_remaining(&item.cont);
buffer_lstrip(&item.buf, 0x00);
size_t len = buffer_remaining(&item.buf);
// Positive integers should start with one 0x00 byte if and only if the most
// significant byte is >= 0x80.
uint8_t msb = 0;
bool prepend_null = (!buffer_peek(&item.cont, &msb) || msb >= 0x80);
bool prepend_null = (!buffer_peek(&item.buf, &msb) || msb >= 0x80);
if (prepend_null) {
len += 1;
}
@ -132,5 +139,5 @@ bool der_reencode_int(BUFFER_READER *reader, BUFFER_WRITER *writer) {
}
}
return buffer_write_buffer(writer, &item.cont);
return buffer_write_buffer(writer, &item.buf);
}

7
crypto/der.h
View File

@ -33,9 +33,14 @@
#define DER_SEQUENCE 0x30
#define DER_INTEGER 0x02
// Struct representing a DER-encoded ASN.1 data value.
typedef struct {
// Single-octet identifier encoding the ASN.1 class, type and tag number.
uint8_t id;
BUFFER_READER cont;
// A buffer containing the entire DER encoding of the data value including the
// tag and length, but with the position indicator initialized to the offset
// of the contents octets.
BUFFER_READER buf;
} DER_ITEM;
bool __wur der_read_length(BUFFER_READER *buf, size_t *len);