In an attempt to assign a zero-length HMAC key, consumers might
incorrectly call:
HMAC_Init_ex(key=NULL, key_len=0)
This does not work as expected since |key==NULL| has special semantics.
This bug may consequently result in uninitialized memory being used for
the HMAC key data.
This workaround doesn't fix all the problems associated with this
pattern, however by defaulting to a zero key the results are more
predictable than before.
BUG=http://crbug.com/449409
Change-Id: I777276d57c61f1c0cce80b18e28a9b063784733f
Reviewed-on: https://boringssl-review.googlesource.com/3040
Reviewed-by: Adam Langley <agl@google.com>
HMAC_CTX_copy's documentation is off. It actually follows the old copy
functions which call FOO_init on dest first. Notably this means that they leak
memory if dest is currently in use.
Add HMAC_CTX_copy_ex as an analog of EVP_MD_CTX_copy and deprecate
HMAC_CTX_copy. (EVP_CIPHER_CTX_copy, in contrast, was correct from the start.)
Change-Id: I48566c858663d3f659bd356200cf862e196576c9
Reviewed-on: https://boringssl-review.googlesource.com/2694
Reviewed-by: Adam Langley <agl@google.com>
The expectation when calling HMAC with key=NULL and keylen=0 is to compute
HMAC on the provided data with a key of length 0 instead of using the
"previous" key, which in the case of HMAC() is whatever bytes happen to be
left on the stack when the HMAC_CTX struct is allocated.
Change-Id: I52a95e262ee4e15f1af3136cb9c07f42f40ce122
Reviewed-on: https://boringssl-review.googlesource.com/2660
Reviewed-by: Adam Langley <agl@google.com>
Initial fork from f2d678e6e89b6508147086610e985d4e8416e867 (1.0.2 beta).
(This change contains substantial changes from the original and
effectively starts a new history.)
