This document presents EPBC, Efficient Error-Propagating Block Chaining, a new and efficient block encryption mode using both plaintext and ciphertext feedback. This encryption mode is similar to another one, IOBC, and was likewise designed to propagate erroneous decryptions of tampered blocks of ciphered data to all following blocks, hence allowing to validate the integrity of that data using a predefined trailing value. However, EPBC is more secure than IOBC, as it is not vulnerable to any known-plaintext attacks, and is more efficient than IOBC. Performance tests ran on a SPARCstation 10/40 show that EPBC is in average 1.2 times faster than IOBC, and 6.3 to 10.9 times faster than a common combination of an encryption mode and a one-way hash function (CBC and MD5).