{"id":68562,"date":"2018-09-07T12:30:12","date_gmt":"2018-09-07T10:30:12","guid":{"rendered":"https:\/\/easy-software.com\/?post_type=glossar&p=68562"},"modified":"2025-06-06T09:31:29","modified_gmt":"2025-06-06T07:31:29","slug":"digital-signature","status":"publish","type":"glossar","link":"https:\/\/easy-software.com\/en\/glossary\/digital-signature\/","title":{"rendered":"Digital signature"},"content":{"rendered":"
In other words, the digital signature<\/a> can be used, on the one hand, to check if and ensure that the email actually comes from the sender shown in the email program. On the other hand, it can be used to check if the contents of the email have been changed during sendin<\/p>\n\n\n\n The procedure for creating a digital signature<\/a> is based on the principle of asymmetric cryptography. Asymmetric here means that a key pair is always used to sign and encrypt a message. Everyone involved in the process has a public and a private \u2013 which is always and consistently kept secret <\/strong>\u2013 key. The two keys form the key pair.<\/p>\n\n\n\n What does this achieve? Alice\u2019s message can only be decrypted with her public key.<\/p>\n\n\n\n If the decryption works, you have proof that<\/p>\n\n\n\n Both the authorship and the integrity<\/strong> of the email are thus proven<\/p>\n\n\n\n However, the message was by no means encrypted by merely signing it. Anyone who has Alice\u2019s public key could have read the email from Alice to Bob \u2013 and in principle that is everyone. Therefore:<\/p>\n\n\n\n In practice, the respective client program handles the signing and encryption. Established procedures for the practical implementation of asymmetric cryptography are S\/MIME (X.509) and PGP or GnuPG. Various algorithms are used (AES, RSA, etc.). A public key infrastructure (PKI)<\/a> and key management systems are often used here.<\/p>\n\n\nHow does the digital signature work \u2013 how are these two goals achieved?<\/h2>\n\n\n\n
Sign<\/h2>\n\n\n\n
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Sign & encrypt<\/h2>\n\n\n\n
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