This paper presents a hierarchical identity-based encryption (HIDE) scheme and a related hierarchical identity-based signature (HIDS) scheme that are secure against chosen-ciphertext attacks in the random oracle model. The HIDE scheme is fully collusion-resistant and efficient, with ciphertext and decryption complexity growing linearly with the depth of the recipient in the hierarchy. The scheme is based on the Bilinear Diffie-Hellman (BDH) problem and uses a bilinear pairing to achieve security. The HIDS scheme is derived from the HIDE scheme and allows for the creation of "escrow shelters" that limit the scope of key escrow. The paper also introduces a dual-identity-based encryption (Dual-HIDE) scheme that reduces ciphertext expansion by leveraging shared secrets between users in the hierarchy. Additionally, the paper discusses methods to restrict key escrow by using authenticated key agreement protocols and authenticated root PKGs. The security of the schemes is based on the difficulty of the BDH problem and the Diffie-Hellman problem in the group G1. The paper also provides extensions and observations, including improvements in encryption efficiency and distributed PKG techniques.This paper presents a hierarchical identity-based encryption (HIDE) scheme and a related hierarchical identity-based signature (HIDS) scheme that are secure against chosen-ciphertext attacks in the random oracle model. The HIDE scheme is fully collusion-resistant and efficient, with ciphertext and decryption complexity growing linearly with the depth of the recipient in the hierarchy. The scheme is based on the Bilinear Diffie-Hellman (BDH) problem and uses a bilinear pairing to achieve security. The HIDS scheme is derived from the HIDE scheme and allows for the creation of "escrow shelters" that limit the scope of key escrow. The paper also introduces a dual-identity-based encryption (Dual-HIDE) scheme that reduces ciphertext expansion by leveraging shared secrets between users in the hierarchy. Additionally, the paper discusses methods to restrict key escrow by using authenticated key agreement protocols and authenticated root PKGs. The security of the schemes is based on the difficulty of the BDH problem and the Diffie-Hellman problem in the group G1. The paper also provides extensions and observations, including improvements in encryption efficiency and distributed PKG techniques.