There is a mixmaster version that allows RSA keys of 4096 bits. http://www.zen19351.zen.co.uk/mixmaster302/ This is compatible with current s/w at size 1024 but for larger keys uses additional HMAC integrity and AES encryption steps over the 3DES and MD5 already present. Temporary test remailers are set up (do not use for real sensitive traffic). Test this new version and be ready for remailer key upgrades. This is the error legacy mixmaster generates with a large RSA key. $ fortune | ./mixmaster --chain=carrots -s test --to=abuse@carrots.org.uk Error: Encryption failed! carrots carrots@carrots.org.uk ad5a9748f33dd704dc85ae1dd1287870 2:3.0.2 CNm 2013-11-06 2014-01-15 -----Begin Mix Key----- ad5a9748f33dd704dc85ae1dd1287870 1026 ABDgYu+FBuHFxPHl1vH23f+V4+YH2NZg4HxFGxA1 QVUlG31H9QjYCjuwpbNOnwmNG6BpGL6CglP7W6T7 bFl2Dv+ptQkASiTm4Wj87w3AdoI+mGXU2bBe4k81 holEIXlCozL+P5Sw6TBKPXkyBBnP/5BBHATl1Q4J FmpX/B7e7ZqlLdkc3wpY4QlXtMF4+KnurKAxUI7e ruVr4W93+hFpJBB6WPP4CZaVEsIuqTKDUndWCcH2 xJMW8eLrqlm/ZR/kGmFTiOio0cM6dhrpaow+OMtg xPktl2joXhJYDZ3tFNJ9MduIrbaXRe9xtD8MqA6c NQBRE9fRM6gl8MfewYPEOTnxliCqoSYEeb7FZBvF IoBQIpJqkddO+zi+pw47TKEoo4eJs74Hq8hN6sA7 7SeJn4Ej9sOxKQgeLeb+RGyCtWdgllIAgWQGuU1q xPQqxCCx6Yo4VKU8GUfE5RtLxKwWCbCWpXJrhHjt g1rL7slvDhkbVUNFj02hq5tmr22+lr3eKW81hiwe 6B8kJV8w+MtFOy1H/IamhwSJyb6xCqbPB7hbobX0 5iHY76BDJQpx8LH/9SeNOkSjO+2x+LzEt9Whz4jT Ll+kxHS6a0lJBWKvWi4ikJV+oDM+XsiuQXE5yL61 jyF/tIX9eYaz3WVZxwEPcVypGVRqrq8jlhWPYpJe mqrW4wAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAQAB -----End Mix Key----- coconuts coconuts@coconuts.org.uk bb6cf51abe871947a759ecb5b97ffa3f 2:3.0.2 MCNm 2013-11-11 2014-01-30 -----Begin Mix Key----- bb6cf51abe871947a759ecb5b97ffa3f 1026 ABCiAmzGS+qdEddcI9isI5Z/7VFu5KewVGYUwhDN hqq2DP49GXEui584aeyCN5llmVGEck9hcYA9DUiw /yVU/pxfaBfjf5PvFSckG+cagcL30hwTUIzz7KEK zyr0eamM1y74kUgMbnsldSdoeS66bundJhKd4z+F xgdLWdf355UIzXq94PXOi51x85A6nUVjfUetsUhW ZbknbCjCUlKkM2zV1Ty1gcxMzE6GoVRUmymYXJda 1cWoHQvITwx/lWGLGVu0cTb09bbFTY1IghviJOaF UkMtMoDqQYFcaYBcmK/2ghmuFZsoIjiyGkvIPliV vMyX8hCUZUYpIHuF65KLfnddCYQek5DqnYNQ3aFT H34MdXWIOZwoGQmy3/JJ66UnDfPOMDQK1nFimBjr SVwDGT4tgbpYxBN7ytqxQxlVxQ99s5BnraLCVlpW BiKhHLS48zZMnlp0S3ffcmaijJ60TKJOR0gkxqAA hxBoszpN+0Z9KSOmDxP/HYM7ZBFzSyFcPGTpqTXp ZFrcIfG64rf8IfVgWryuubYUkcyy04aygSzHBMl6 yln4vGKJJ8/z/zd9HEvATKkJ4kqiscY6yV96D2hl KKtbGn2QUVCbH6v64wF0/a5d+z2ZKrEOYhL7EmPI gLGQCcv9W7m5tdaBa4LXu09dArWNPwmwpOOC787T yp42ewAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAQAB -----End Mix Key-----