我使用两组不同的密钥测试，发现第一组在签名计算时就返回错误，第二组是可以成功的。
/*
var publicKey = []byte(-----BEGIN PUBLIC KEY----- MDwwDQYJKoZIhvcNAQEBBQADKwAwKAIhAMnq1wtxSjuMRPKULlvJxx//CQWKxqx2 TzGHDmOQZVT/AgMBAAE= -----END PUBLIC KEY-----)

var privateKey = []byte(-----BEGIN RSA PRIVATE KEY----- MIGrAgEAAiEAyerXC3FKO4xE8pQuW8nHH/8JBYrGrHZPMYcOY5BlVP8CAwEAAQIg HNTpq/qbTPF0jubVz8l6IziHlW5rHt3r8etpnTZMuRECEQDob9bD+4LzwtK+1AJy YPL7AhEA3mL2sjTi5vp0y04BC1ymzQIRALIl9d9kB+w4qDnmWLG9qL0CEQDJ0P/W e95LBZIGipSyDfQlAhBaDYtiehP+XMDPcv/x9Kj0 -----END RSA PRIVATE KEY-----)
*/

var publicKey = []byte(-----BEGIN PUBLIC KEY----- MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDCFENGw33yGihy92pDjZQhl0C3 6rPJj+CvfSC8+q28hxA161QFNUd13wuCTUcq0Qd2qsBe/2hFyc2DCJJg0h1L78+6 Z4UMR7EOcpfdUE9Hf3m/hs+FUR45uBJeDK1HSFHD8bHKD6kv8FPGfJTotc+2xjJw oYi+1hqp1fIekaxsyQIDAQAB -----END PUBLIC KEY-----)

var privateKey = []byte(-----BEGIN RSA PRIVATE KEY----- MIICXgIBAAKBgQDCFENGw33yGihy92pDjZQhl0C36rPJj+CvfSC8+q28hxA161QF NUd13wuCTUcq0Qd2qsBe/2hFyc2DCJJg0h1L78+6Z4UMR7EOcpfdUE9Hf3m/hs+F UR45uBJeDK1HSFHD8bHKD6kv8FPGfJTotc+2xjJwoYi+1hqp1fIekaxsyQIDAQAB AoGBAJR8ZkCUvx5kzv+utdl7T5MnordT1TvoXXJGXK7ZZ+UuvMNUCdN2QPc4sBiA QWvLw1cSKt5DsKZ8UETpYPy8pPYnnDEz2dDYiaew9+xEpubyeW2oH4Zx71wqBtOK kqwrXa/pzdpiucRRjk6vE6YY7EBBs/g7uanVpGibOVAEsqH1AkEA7DkjVH28WDUg f1nqvfn2Kj6CT7nIcE3jGJsZZ7zlZmBmHFDONMLUrXR/Zm3pR5m0tCmBqa5RK95u 412jt1dPIwJBANJT3v8pnkth48bQo/fKel6uEYyboRtA5/uHuHkZ6FQF7OUkGogc mSJluOdc5t6hI1VsLn0QZEjQZMEOWr+wKSMCQQCC4kXJEsHAve77oP6HtG/IiEn7 kpyUXRNvFsDE0czpJJBvL/aRFUJxuRK91jhjC68sA7NsKMGg5OXb5I5Jj36xAkEA gIT7aFOYBFwGgQAQkWNKLvySgKbAZRTeLBacpHMuQdl1DfdntvAyqpAZ0lY0RKmW G6aFKaqQfOXKCyWoUiVknQJAXrlgySFci/2ueKlIE1QqIiLSZ8V8OlpFLRnb1pzI 7U1yQXnTAEFYM560yJlzUpOb1V4cScGd365tiSMvxLOvTA== -----END RSA PRIVATE KEY-----)
从密钥长度上看这两组密钥的长度不一样，但都是可用的密钥，不清楚为什么第一组不可以

github.com/89hmdys/toast/rsa

mode.go:8: imported and not used: "hash"