Emacs: Failed to verify signatur

出处：https://emacs.stackexchange.com/questions/233/how-to-proceed-on-package-el-signature-check-failure

问题可能呈现的状态

package--check-signature: Failed to verify signature 
   ascii-art-to-unicode-1.9.el.sig: ("No public key 
   for 474F05837FBDEF9B created at 2014-09-24T16:20:01+0200 
   using DSA")

解决方法

1. set package-check-signature to nil, e.g. M-: (setq package-check-signature nil) RET
2. download the package gnu-elpa-keyring-update and run the function with the same name, e.g. M-x package-install RET gnu-elpa-keyring-update RET.
3. reset package-check-signature to the default value allow-unsigned，e.g. M-: (setq package-check-signature t) RET