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diff --git a/lib/crypto/doc/src/new_api.xml b/lib/crypto/doc/src/new_api.xml new file mode 100644 index 0000000000..aacf5e4f76 --- /dev/null +++ b/lib/crypto/doc/src/new_api.xml @@ -0,0 +1,329 @@ +<?xml version="1.0" encoding="utf-8" ?> +<!DOCTYPE chapter SYSTEM "chapter.dtd"> + +<chapter> + <header> + <copyright> + <year>2014</year><year>2019</year> + <holder>Ericsson AB. All Rights Reserved.</holder> + </copyright> + <legalnotice> + The contents of this file are subject to the Erlang Public License, + Version 1.1, (the "License"); you may not use this file except in + compliance with the License. You should have received a copy of the + Erlang Public License along with this software. If not, it can be + retrieved online at http://www.erlang.org/. + + Software distributed under the License is distributed on an "AS IS" + basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See + the License for the specific language governing rights and limitations + under the License. + + </legalnotice> + + <title>New and Old API</title> + <prepared>Hans Nilsson</prepared> + <docno></docno> + <date>2019-08-22</date> + <rev>A</rev> + <file>new_api.xml</file> + </header> + <p> + This chapter describes the new api to encryption and decryption. + </p> + + <section> + <title>Background</title> + <p>The CRYPTO app has evolved during its lifetime. Since also the OpenSSL cryptolib has changed the + API several times, there are parts of the CRYPTO app that uses a very old one internally and + other parts that uses the latest one. The internal definitions of e.g cipher names was a bit hard + to maintain. + </p> + <p>It turned out that using the old api in the new way (more about that later), and still keep it + backwards compatible, was not possible. Specially as more precision in the error messages is desired + it could not be combined with the old standard. + </p> + <p>Therefore the old api (see next section) is kept for now but internally implemented with new primitives. + </p> + </section> + + <section> + <title>The old API</title> + <p>The old functions - not recommended for new programs - are for chipers:</p> + <list> + <item><seealso marker="crypto#block_encrypt-3">block_encrypt/3</seealso></item> + <item><seealso marker="crypto#block_encrypt-4">block_encrypt/4</seealso></item> + <item><seealso marker="crypto#block_decrypt-3">block_decrypt/3</seealso></item> + <item><seealso marker="crypto#block_decrypt-4">block_decrypt/4</seealso></item> + <item><seealso marker="crypto#stream_init-2">stream_init/2</seealso></item> + <item><seealso marker="crypto#stream_init-2">stream_init/3</seealso></item> + <item><seealso marker="crypto#stream_encrypt-2">stream_encrypt/2</seealso></item> + <item><seealso marker="crypto#stream_decrypt-2">stream_decrypt/2</seealso></item> + </list> + <p>for lists of supported algorithms:</p> + <list> + <item><seealso marker="crypto#supports-0">supports/0</seealso></item> + </list> + <p>and for MACs (Message Authentication Codes):</p> + <list> + <item><seealso marker="crypto#cmac-3">cmac/3</seealso></item> + <item><seealso marker="crypto#cmac-4">cmac/4</seealso></item> + <item><seealso marker="crypto#hmac-3">hmac/3</seealso></item> + <item><seealso marker="crypto#hmac-4">hmac/4</seealso></item> + <item><seealso marker="crypto#hmac_init-2">hmac_init/2</seealso></item> + <item><seealso marker="crypto#hmac_update-2">hmac_update/2</seealso></item> + <item><seealso marker="crypto#hmac_final-1">hmac_final/1</seealso></item> + <item><seealso marker="crypto#hmac_final_n-2">hmac_final_n/2</seealso></item> + <item><seealso marker="crypto#poly1305-2">poly1305/2</seealso></item> + </list> + <p>They are not deprecated for now, but may be in a future release. + </p> + </section> + + <section> + <title>The new API</title> + <section> + <title>Encryption and decryption</title> + <p>The new functions for encrypting or decrypting one single binary are: + </p> + <list> + <item><seealso marker="crypto#crypto_one_time/4">crypto_one_time/4</seealso></item> + <item><seealso marker="crypto#crypto_one_time/5">crypto_one_time/5</seealso></item> + <item><seealso marker="crypto#crypto_one_time_aead/6">crypto_one_time_aead/6</seealso></item> + <item><seealso marker="crypto#crypto_one_time_aead/7">crypto_one_time_aead/7</seealso></item> + </list> + <p>In those functions the internal crypto state is first created and initialized + with the cipher type, the key and possibly other data. Then the single binary is encrypted + or decrypted, + the crypto state is de-allocated and the result of the crypto operation is returned. + </p> + <p>The <c>crypto_one_time_aead</c> functions are for the ciphers of mode <c>ccm</c> or + <c>gcm</c>, and for the cipher <c>chacha20-poly1305</c>. + </p> + <p>For repeated encryption or decryption of a text divided in parts, where the internal + crypto state is initialized once, and then many binaries are encrypted or decrypted with + the same state, the functions are: + </p> + <list> + <item><seealso marker="crypto#crypto_init/4">crypto_init/4</seealso></item> + <item><seealso marker="crypto#crypto_init/3">crypto_init/3</seealso></item> + <item><seealso marker="crypto#crypto_update/2">crypto_update/2</seealso></item> + </list> + <p>The <c>crypto_init</c> initialies an internal cipher state, and one or more calls of + <c>crypto_update</c> does the acual encryption or decryption. Note that AEAD ciphers + can't be handled this way due to their nature. + </p> + <p>For repeated encryption or decryption of a text divided in parts where the + same cipher and same key is used, but a new initialization vector (nounce) should be applied + for each part, the functions are: + </p> + <list> + <item><seealso marker="crypto#crypto_dyn_iv_init/3">crypto_dyn_iv_init/3</seealso></item> + <item><seealso marker="crypto#crypto_dyn_iv_update/3">crypto_dyn_iv_update/3</seealso></item> + </list> + <p>An example of where those functions are needed, is when handling the TLS protocol.</p> + <p>For information about available algorithms, use: + </p> + <list> + <item><seealso marker="crypto#supports-1">supports/1</seealso></item> + <item><seealso marker="crypto#hash_info-1">hash_info/1</seealso></item> + <item><seealso marker="crypto#cipher_info-1">cipher_info/1</seealso></item> + </list> + </section> + + <section> + <title>MACs (Message Authentication Codes)</title> + <p>The new functions for calculating a MAC of a single piece of text are:</p> + <list> + <item><seealso marker="crypto#mac-3">mac/3</seealso></item> + <item><seealso marker="crypto#mac-4">mac/4</seealso></item> + <item><seealso marker="crypto#macN-4">macN/4</seealso></item> + <item><seealso marker="crypto#macN-5">macN/5</seealso></item> + </list> + <p>For calculating a MAC of a text divided in parts use:</p> + <list> + <item><seealso marker="crypto#mac_init-2">mac_init/2</seealso></item> + <item><seealso marker="crypto#mac_init-3">mac_init/3</seealso></item> + <item><seealso marker="crypto#mac_update-2">mac_update/2</seealso></item> + <item><seealso marker="crypto#mac_final-1">mac_final/1</seealso></item> + <item><seealso marker="crypto#mac_finalN-2">mac_finalN/2</seealso></item> + </list> + </section> + </section> + + <section> + <title>Examples of the new api</title> + <section> + <title>Examples of crypto_init/4 and crypto_update/2</title> + <p>The functions <seealso marker="crypto#crypto_init/4">crypto_init/4</seealso> + and <seealso marker="crypto#crypto_update/2">crypto_update/2</seealso> are intended + to be used for encrypting or decrypting a sequence of blocks. First one call of + <c>crypto_init/4</c> initialises the crypto context. One or more calls <c>crypto_update/2</c> + does the actual encryption or decryption for each block. + </p> + <p>This example shows first the encryption of two blocks and then decryptions of the cipher + text, but divided into three blocks just to show that it is possible to divide the plain text and + cipher text differently for some ciphers:</p> + <code type="erl"> + 1> crypto:start(). + ok + 2> Key = <<1:128>>. + <<0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1>> + 3> IV = <<0:128>>. + <<0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0>> + 4> StateEnc = crypto:crypto_init(aes_128_ctr, Key, IV, true). % encrypt -> true + #Ref<0.3768901617.1128660993.124047> + 5> crypto:crypto_update(StateEnc, <<"First bytes">>). + <<67,44,216,166,25,130,203,5,66,6,162>> + 6> crypto:crypto_update(StateEnc, <<"Second bytes">>). + <<16,79,94,115,234,197,94,253,16,144,151,41>> + 7> + 7> StateDec = crypto:crypto_init(aes_128_ctr, Key, IV, false). % decrypt -> false + #Ref<0.3768901617.1128660994.124255> + 8> crypto:crypto_update(StateDec, <<67,44,216,166,25,130,203>>). + <<"First b">> + 9> crypto:crypto_update(StateDec, <<5,66,6,162,16,79,94,115,234,197, + 94,253,16,144,151>>). + <<"ytesSecond byte">> + 10> crypto:crypto_update(StateDec, <<41>>). + <<"s">> + 11> + </code> + <p>Note that the internal data that the <c>StateEnc</c> and <c>StateDec</c> references are + destructivly updated by the calls to <seealso marker="crypto#crypto_update/2">crypto_update/2</seealso>. + This is to gain time in the calls of the nifs interfacing the cryptolib. In a loop where the + state is saved in the loop's state, it also saves one update of the loop state per crypto operation. + </p> + <p>For example, a simple server receiving text parts to encrypt and send the result back to the + one who sent them (the <c>Requester</c>): + </p> + <code type="erl"> + encode(Crypto, Key, IV) -> + crypto_loop(crypto:crypto_init(Crypto, Key, IV, true)). + + crypto_loop(State) -> + receive + {Text, Requester} -> + Requester ! crypto:crypto_update(State, Text), + loop(State) + end. + </code> + </section> + + <section> + <title>Example of crypto_one_time/5</title> + <p>The same example as in the + <seealso marker="#examples-of-crypto_init-4-and-crypto_update-2">previous section</seealso>, + but now with one call to <seealso marker="crypto#crypto_one_time/5">crypto_one_time/5</seealso>: + </p> + <code> + 1> Key = <<1:128>>. + <<0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1>> + 2> IV = <<0:128>>. + <<0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0>> + 3> Txt = [<<"First bytes">>,<<"Second bytes">>]. + [<<"First bytes">>,<<"Second bytes">>] + 4> crypto:crypto_one_time(aes_128_ctr, Key, IV, Txt, true). + <<67,44,216,166,25,130,203,5,66,6,162,16,79,94,115,234, + 197,94,253,16,144,151,41>> + 5> + </code> + <p>The <c>[<<"First bytes">>,<<"Second bytes">>]</c> could of course have been one + single binary: <c><<"First bytesSecond bytes">></c>. + </p> + </section> + + <section> + <title>Example of crypto_one_time_aead/6</title> + <p>The same example as in the + <seealso marker="#example-of-crypto_one_time-5">previous section</seealso>, + but now with one call to <seealso marker="crypto#crypto_one_time_aead/6">crypto_one_time_aead/6</seealso>: + </p> + <code> + 1> Key = <<1:128>>. + <<0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1>> + 2> IV = <<0:128>>. + <<0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0>> + 3> Txt = [<<"First bytes">>,<<"Second bytes">>]. + [<<"First bytes">>,<<"Second bytes">>] + 4> AAD = <<"Some bytes">>. + <<"Some bytes">> + 5> crypto:crypto_one_time_aead(aes_128_gcm, Key, IV, Txt, AAD, true). + {<<240,130,38,96,130,241,189,52,3,190,179,213,132,1,72, + 192,103,176,90,104,15,71,158>>, + <<131,47,45,91,142,85,9,244,21,141,214,71,31,135,2,155>>} + 9> + </code> + <p>The <c>[<<"First bytes">>,<<"Second bytes">>]</c> could of course have been one + single binary: <c><<"First bytesSecond bytes">></c>. + </p> + </section> + + <section> + <title>Example of mac_init mac_update and mac_final</title> + <code> + 1> Key = <<1:128>>. + <<0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1>> + 2> StateMac = crypto:mac_init(cmac, aes_128_cbc, Key). + #Ref<0.2424664121.2781478916.232610> + 3> crypto:mac_update(StateMac, <<"First bytes">>). + #Ref<0.2424664121.2781478916.232610> + 4> crypto:mac_update(StateMac, " "). + #Ref<0.2424664121.2781478916.232610> + 5> crypto:mac_update(StateMac, <<"last bytes">>). + #Ref<0.2424664121.2781478916.232610> + 6> crypto:mac_final(StateMac). + <<68,191,219,128,84,77,11,193,197,238,107,6,214,141,160, + 249>> + 7> + </code> + <p>and compare the result with a single calculation just for this example:</p> + <code> + 7> crypto:mac(cmac, aes_128_cbc, Key, "First bytes last bytes"). + <<68,191,219,128,84,77,11,193,197,238,107,6,214,141,160, + 249>> + 8> v(7) == v(6). + true + 9> + </code> + </section> + + </section> + + <section> + <title>Retired cipher names</title> + <p>This table lists the retired cipher names in the first column and suggests names to replace them with + in the second column. + </p> + <p>The new names follows the OpenSSL libcrypto names. The format is ALGORITM_KEYSIZE_MODE. + </p> + <p>Examples of algorithms are aes, chacha20 and des. The keysize is the number of bits + and examples of the mode are cbc, ctr and gcm. The mode may be followed by a number depending + on the mode. An example is the ccm mode which has a variant called ccm8 where the so called tag + has a length of eight bits. + </p> + <p>The old names had by time lost any common naming convention which the new names now introduces. The new names include + the key length which improves the error checking in the lower levels of the crypto application. + </p> + + <table> + <row><cell><strong>Instead of:</strong></cell> <cell><strong>Use:</strong> </cell></row> + + <row><cell><c>aes_cbc128</c> </cell> <cell> <c>aes_128_cbc</c> </cell></row> + <row><cell><c>aes_cbc256</c> </cell> <cell> <c>aes_256_cbc</c> </cell></row> + <row><cell><c>aes_cbc</c> </cell> <cell> <c>aes_128_cbc, aes_192_cbc, aes_256_cbc</c></cell></row> + <row><cell><c>aes_ccm</c> </cell> <cell> <c>aes_128_ccm, aes_192_ccm, aes_256_ccm</c></cell></row> + <row><cell><c>aes_cfb128</c> </cell> <cell> <c>aes_128_cfb128, aes_192_cfb128, aes_256_cfb128</c></cell></row> + <row><cell><c>aes_cfb8</c> </cell> <cell> <c>aes_128_cfb8, aes_192_cfb8, aes_256_cfb8</c></cell></row> + <row><cell><c>aes_ctr</c> </cell> <cell> <c>aes_128_ctr, aes_192_ctr, aes_256_ctr</c></cell></row> + <row><cell><c>aes_gcm</c> </cell> <cell> <c>aes_128_gcm, aes_192_gcm, aes_256_gcm</c></cell></row> + <row><cell><c>des3_cbc</c> </cell> <cell> <c>des_ede3_cbc</c></cell></row> + <row><cell><c>des3_cbf</c> </cell> <cell> <c>des_ede3_cfb</c></cell></row> + <row><cell><c>des3_cfb</c> </cell> <cell> <c>des_ede3_cfb</c></cell></row> + <row><cell><c>des_ede3</c> </cell> <cell> <c>des_ede3_cbc</c></cell></row> + <row><cell><c>des_ede3_cbf</c> </cell> <cell> <c>des_ede3_cfb</c></cell></row> + <tcaption></tcaption> + </table> + </section> + +</chapter> |