The two-volume proceedings LNCS 9056 + 9057 constitutes the proceedings of the 34th Annual International Conference on the Theory and Applications of Cryptographic Techniques EUROCRYPT 2015 held in Sofia Bulgaria in April 2015. The 57 full papers included in these volumes were carefully reviewed and selected from 194 submissions. The papers are organized in topical sections named: honorable mentions random number generators number field sieve algorithmic cryptanalysis symmetric cryptanalysis hash functions evaluation implementation masking fully homomorphic encryption related-key attacks fully monomorphic encryption efficient two-party protocols symmetric cryptanalysis lattices signatures zero-knowledge proofs leakage-resilient cryptography garbled circuits crypto currencies secret sharing outsourcing computations obfuscation and e-voting multi-party computations encryption resistant protocols key exchange quantum cryptography and discrete logarithms.