diff options
| -rw-r--r-- | doc/lispref/text.texi | 12 | ||||
| -rw-r--r-- | lisp/subr.el | 8 | ||||
| -rw-r--r-- | src/fns.c | 11 |
3 files changed, 21 insertions, 10 deletions
diff --git a/doc/lispref/text.texi b/doc/lispref/text.texi index 7ce54f59c69..955ad6130ca 100644 --- a/doc/lispref/text.texi +++ b/doc/lispref/text.texi @@ -4710,12 +4710,12 @@ that you have an unaltered copy of that data. SHA-1, SHA-2, SHA-224, SHA-256, SHA-384 and SHA-512. MD5 is the oldest of these algorithms, and is commonly used in @dfn{message digests} to check the integrity of messages transmitted over a -network. MD5 is not collision resistant (i.e., it is possible to -deliberately design different pieces of data which have the same MD5 -hash), so you should not used it for anything security-related. A -similar theoretical weakness also exists in SHA-1. Therefore, for -security-related applications you should use the other hash types, -such as SHA-2. +network. MD5 and SHA-1 are not collision resistant (i.e., it is +possible to deliberately design different pieces of data which have +the same MD5 or SHA-1 hash), so you should not use them for anything +security-related. For security-related applications you should use +the other hash types, such as SHA-2 (e.g. @code{sha256} or +@code{sha512}). @defun secure-hash-algorithms This function returns a list of symbols representing algorithms that diff --git a/lisp/subr.el b/lisp/subr.el index 0b47da884b7..45b99a82d2b 100644 --- a/lisp/subr.el +++ b/lisp/subr.el @@ -3120,11 +3120,15 @@ Otherwise, return nil." raw-field))) (defun sha1 (object &optional start end binary) - "Return the SHA1 (Secure Hash Algorithm) of an OBJECT. + "Return the SHA-1 (Secure Hash Algorithm) of an OBJECT. OBJECT is either a string or a buffer. Optional arguments START and END are character positions specifying which portion of OBJECT for computing the hash. If BINARY is non-nil, return a string in binary -form." +form. + +Note that SHA-1 is not collision resistant and should not be used +for anything security-related. See `secure-hash' for +alternatives." (secure-hash 'sha1 object start end binary)) (defun function-get (f prop &optional autoload) diff --git a/src/fns.c b/src/fns.c index f45c729cfaf..2314b4699e7 100644 --- a/src/fns.c +++ b/src/fns.c @@ -5376,7 +5376,10 @@ If OBJECT is a string, the most preferred coding system (see the command `prefer-coding-system') is used. If NOERROR is non-nil, silently assume the `raw-text' coding if the -guesswork fails. Normally, an error is signaled in such case. */) +guesswork fails. Normally, an error is signaled in such case. + +Note that MD5 is not collision resistant and should not be used for +anything security-related. See `secure-hash' for alternatives. */) (Lisp_Object object, Lisp_Object start, Lisp_Object end, Lisp_Object coding_system, Lisp_Object noerror) { return secure_hash (Qmd5, object, start, end, coding_system, noerror, Qnil); @@ -5393,7 +5396,11 @@ whole OBJECT. The full list of algorithms can be obtained with `secure-hash-algorithms'. -If BINARY is non-nil, returns a string in binary form. */) +If BINARY is non-nil, returns a string in binary form. + +Note that MD5 and SHA-1 are not collision resistant and should not be +used for anything security-related. For these applications, use one +of the other hash types instead, e.g. sha256 or sha512. */) (Lisp_Object algorithm, Lisp_Object object, Lisp_Object start, Lisp_Object end, Lisp_Object binary) { return secure_hash (algorithm, object, start, end, Qnil, Qnil, binary); |