Implementing MD5: Inconsistent endianness?
So I tried implementing the MD5 algorithm according to RFC1321 in C# and it works, but there is one thing about the way the padding is performed that I don't understand, here's an example:
If I want to hash the string "1" (without the quotation marks) this results in the following bit representation: 10001100
The next step is appending a single "1"-Bit, represented by 00000001 (big endian), which is followed by "0"-Bits, followed by a 64-bit representation of the length of the original message (low-order word first).
Since the length of the original message is 8 (Bits) I expected 00000000000000000000000000001000 00000000000000000000000000000000 to be appended (low-order word first). However this does not result in the correct hash value, but appending 00010000000000000000000000000000 00000000000000000000000000000000 does.
This looks as if suddenly the little-endian format is being used, but that does not really seem to make any sense at all, so I guess there must be something else that I am missing?
hash byte md5 bit
asked Feb 15 '18 at 23:58
user8488823user8488823
154
add a comment |
So I tried implementing the MD5 algorithm according to RFC1321 in C# and it works, but there is one thing about the way the padding is performed that I don't understand, here's an example:
If I want to hash the string "1" (without the quotation marks) this results in the following bit representation: 10001100
The next step is appending a single "1"-Bit, represented by 00000001 (big endian), which is followed by "0"-Bits, followed by a 64-bit representation of the length of the original message (low-order word first).
Since the length of the original message is 8 (Bits) I expected 00000000000000000000000000001000 00000000000000000000000000000000 to be appended (low-order word first). However this does not result in the correct hash value, but appending 00010000000000000000000000000000 00000000000000000000000000000000 does.
This looks as if suddenly the little-endian format is being used, but that does not really seem to make any sense at all, so I guess there must be something else that I am missing?
hash byte md5 bit
asked Feb 15 '18 at 23:58
user8488823user8488823
154
add a comment |
So I tried implementing the MD5 algorithm according to RFC1321 in C# and it works, but there is one thing about the way the padding is performed that I don't understand, here's an example:
If I want to hash the string "1" (without the quotation marks) this results in the following bit representation: 10001100
The next step is appending a single "1"-Bit, represented by 00000001 (big endian), which is followed by "0"-Bits, followed by a 64-bit representation of the length of the original message (low-order word first).
Since the length of the original message is 8 (Bits) I expected 00000000000000000000000000001000 00000000000000000000000000000000 to be appended (low-order word first). However this does not result in the correct hash value, but appending 00010000000000000000000000000000 00000000000000000000000000000000 does.
This looks as if suddenly the little-endian format is being used, but that does not really seem to make any sense at all, so I guess there must be something else that I am missing?
hash byte md5 bit
asked Feb 15 '18 at 23:58
user8488823user8488823
154
So I tried implementing the MD5 algorithm according to RFC1321 in C# and it works, but there is one thing about the way the padding is performed that I don't understand, here's an example:
If I want to hash the string "1" (without the quotation marks) this results in the following bit representation: 10001100
The next step is appending a single "1"-Bit, represented by 00000001 (big endian), which is followed by "0"-Bits, followed by a 64-bit representation of the length of the original message (low-order word first).
Since the length of the original message is 8 (Bits) I expected 00000000000000000000000000001000 00000000000000000000000000000000 to be appended (low-order word first). However this does not result in the correct hash value, but appending 00010000000000000000000000000000 00000000000000000000000000000000 does.
This looks as if suddenly the little-endian format is being used, but that does not really seem to make any sense at all, so I guess there must be something else that I am missing?
hash byte md5 bit
hash byte md5 bit
asked Feb 15 '18 at 23:58
user8488823user8488823
154
asked Feb 15 '18 at 23:58
user8488823user8488823
154
asked Feb 15 '18 at 23:58
user8488823user8488823
154
asked Feb 15 '18 at 23:58
user8488823user8488823
154
asked Feb 15 '18 at 23:58
user8488823user8488823
154
154
add a comment |
add a comment |
1 Answer
1
active
oldest
votes
Yes, for md5 you have to add message length in little-endian.
So, message representation for "1" -> 49 -> 00110001, followed by single bit and zeroes. And after add message length in reversed order of bytes (the least significant byte first).
You could also check permutations step by step on this site: https://cse.unl.edu/~ssamal/crypto/genhash.php.
answered Nov 23 '18 at 15:43
MrBlackMrBlack
695
add a comment |
Your Answer
StackExchange.ifUsing("editor", function () {
StackExchange.using("externalEditor", function () {
StackExchange.using("snippets", function () {
StackExchange.snippets.init();
});
});
}, "code-snippets");
StackExchange.ready(function() {
var channelOptions = {
tags: "".split(" "),
id: "1"
};
initTagRenderer("".split(" "), "".split(" "), channelOptions);
StackExchange.using("externalEditor", function() {
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled) {
StackExchange.using("snippets", function() {
createEditor();
});
}
else {
createEditor();
}
});
function createEditor() {
StackExchange.prepareEditor({
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: true,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: 10,
bindNavPrevention: true,
postfix: "",
imageUploader: {
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
},
onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
});
}
});
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f48818204%2fimplementing-md5-inconsistent-endianness%23new-answer', 'question_page');
}
);
Post as a guest
Required, but never shown
1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
Yes, for md5 you have to add message length in little-endian.
So, message representation for "1" -> 49 -> 00110001, followed by single bit and zeroes. And after add message length in reversed order of bytes (the least significant byte first).
You could also check permutations step by step on this site: https://cse.unl.edu/~ssamal/crypto/genhash.php.
answered Nov 23 '18 at 15:43
MrBlackMrBlack
695
add a comment |
Yes, for md5 you have to add message length in little-endian.
So, message representation for "1" -> 49 -> 00110001, followed by single bit and zeroes. And after add message length in reversed order of bytes (the least significant byte first).
You could also check permutations step by step on this site: https://cse.unl.edu/~ssamal/crypto/genhash.php.
answered Nov 23 '18 at 15:43
MrBlackMrBlack
695
add a comment |
Yes, for md5 you have to add message length in little-endian.
So, message representation for "1" -> 49 -> 00110001, followed by single bit and zeroes. And after add message length in reversed order of bytes (the least significant byte first).
You could also check permutations step by step on this site: https://cse.unl.edu/~ssamal/crypto/genhash.php.
answered Nov 23 '18 at 15:43
MrBlackMrBlack
695
Yes, for md5 you have to add message length in little-endian.
So, message representation for "1" -> 49 -> 00110001, followed by single bit and zeroes. And after add message length in reversed order of bytes (the least significant byte first).
You could also check permutations step by step on this site: https://cse.unl.edu/~ssamal/crypto/genhash.php.
answered Nov 23 '18 at 15:43
MrBlackMrBlack
695
answered Nov 23 '18 at 15:43
MrBlackMrBlack
695
answered Nov 23 '18 at 15:43
MrBlackMrBlack
695
answered Nov 23 '18 at 15:43
MrBlackMrBlack
695
695
add a comment |
add a comment |
Thanks for contributing an answer to Stack Overflow!
- Please be sure to answer the question. Provide details and share your research!
But avoid …
- Asking for help, clarification, or responding to other answers.
- Making statements based on opinion; back them up with references or personal experience.
To learn more, see our tips on writing great answers.
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f48818204%2fimplementing-md5-inconsistent-endianness%23new-answer', 'question_page');
}
);
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
