因此，我尝试使用 OpenSSL 创建 CMS 签名消息，但遇到了一些困难。以下是 OpenSSL 文档的内容：
Create a cleartext signed message:
openssl cms -sign -in message.txt -text -out mail.msg \
-signer mycert.pem
我尝试过但出现以下错误：
unable to load signing key file
140516137625232:error:0906D06C:PEM routines:PEM_read_bio:no start line:pem_lib.c:703:Expecting: ANY PRIVATE KEY
我的 mycert.pem 内容：
-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----
我尝试用私有 RSA 密钥替换 mycert.pem。例如。
-----BEGIN RSA PRIVATE KEY-----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-----END RSA PRIVATE KEY-----
但这给了我这个错误：
unable to load signing key file
139866924107408:error:0906D06C:PEM routines:PEM_read_bio:no start line:pem_lib.c:703:Expecting: TRUSTED CERTIFICATE
也许 mycert.pem 需要是 PKCS12 格式的密钥？我尝试使用以下命令进行转换：
包括一些额外的证书：
openssl pkcs12 -export -in file.pem -out file.p12 -name "My Certificate" \
-certfile othercerts.pem
其中 file.pem 是私钥，othercerts.pem 是 X509 证书，但这导致我出现unable to load certificates错误。
有任何想法吗？